AVR Microcontroller with Core Independent Peripherals...

ATmega324PB AVR Microcontroller with Core Independent Peripherals

and PicoPower technology

Introduction

The picoPower ATmega324PB is a low-power CMOS 8-bit microcontroller based on the AVR enhancedRISC architecture. By executing powerful instructions in a single clock cycle, the ATmega324PB achievesthroughputs close to 1MIPS per MHz. This empowers system designers to optimize the device for powerconsumption versus processing speed.

Feature

High Performance, Low Power AVR 8-Bit Microcontroller Family Advanced RISC Architecture

131 Powerful Instructions Most Single Clock Cycle Execution 32 x 8 General Purpose Working Registers Fully Static Operation Up to 20 MIPS Throughput at 20MHz On-Chip 2-cycle Multiplier

High Endurance Non-Volatile Memory Segments 32KBytes of In-System Self-Programmable Flash Program Memory 1KBytes EEPROM 2KBytes Internal SRAM Write/Erase Cycles: 10,000 Flash/100,000 EEPROM Data Retention: 20 Years at 85C Optional Boot Code Section with Independent Lock Bits

In-System Programming by On-chip Boot Program True Read-While-Write Operation

Programming Lock for Software Security JTAG (IEEE std. 1149.1 Compliant) Interface

Boundary-Scan Capabilities According to the JTAG Standard Extensive On-chip Debug Support Programming of Flash, EEPROM, Fuses, and Lock Bits Through the JTAG Interface

Peripheral Features Peripheral Touch Controller (PTC)

Capacitive Touch Buttons, Sliders and Wheels 32 Self-Sap Channels and 256 Mutual Cap Channels

Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode

2017 Microchip Technology Inc. Datasheet Complete DS40001908A-page 1

Three 16-bit Timer/Counters with Separate Prescaler, Compare Mode, and Capture Mode Real Time Counter with Separate Oscillator Ten PWM Channels 8-Channel 10-Bit ADC

Differential Mode with Selectable Gain at 1, 10 or 200 Three Programmable Serial USARTs Two Master/Slave SPI Serial Interfaces Two Byte-oriented 2-wire Serial Interfaces (Philips I2C Compatible) Programmable Watchdog Timer with Separate On-chip Oscillator On-chip Analog Comparator Interrupt and Wake-up on Pin Change

Special Microcontroller Features Power-on Reset and Programmable Brown-out Detection Internal 8 MHz Calibrated Oscillator External and Internal Interrupt Sources Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended

Standby Clock Failure Detection Mechanism and Switch to Internal 8 MHz RC Oscillator in case of Failure Individual Serial Number to Represent a Unique ID

I/O and Packages 39 Programmable I/O Lines 44-Pin TQFP and 44-Pin QFN /MLF

Operating Voltage: 1.8 - 5.5V

Temperature Range: -40C to 105C

Speed Grade: 0 - 4MHz @ 1.8 - 5.5V 0 - 10MHz @ 2.7 - 5.5.V 0 - 20MHz @ 4.5 - 5.5V

Power Consumption at 1MHz, 1.8V, 25C Active Mode: 0.24mA Power-Down Mode: 0.2A Power-Save Mode: 1.3A (Including 32kHz RTC)

ATmega324PB


Table of Contents

Introduction......................................................................................................................1

Feature............................................................................................................................ 1

1. Description...............................................................................................................10

2. Configuration Summary........................................................................................... 11

3. Ordering Information ...............................................................................................12

4. Block Diagram......................................................................................................... 13

5. Pin Configurations................................................................................................... 145.1. Pin Descriptions......................................................................................................................... 14

6. I/O Multiplexing........................................................................................................16

7. General Information.................................................................................................187.1. Resources.................................................................................................................................. 187.2. About Code Examples................................................................................................................18

8. AVR CPU Core........................................................................................................ 198.1. Overview.................................................................................................................................... 198.2. ALU Arithmetic Logic Unit....................................................................................................... 208.3. Status Register...........................................................................................................................208.4. General Purpose Register File...................................................................................................228.5. Stack Pointer..............................................................................................................................238.6. Accessing 16-bit Registers.........................................................................................................248.7. Instruction Execution Timing...................................................................................................... 248.8. Reset and Interrupt Handling..................................................................................................... 25

9. AVR Memories.........................................................................................................289.1. Overview.................................................................................................................................... 289.2. In-System Reprogrammable Flash Program Memory................................................................289.3. SRAM Data Memory.................................................................................................................. 299.4. EEPROM Data Memory............................................................................................................. 309.5. I/O Memory.................................................................................................................................319.6. Register Description...................................................................................................................32

10. System Clock and Clock Options............................................................................ 3810.1. Clock Systems and Their Distribution........................................................................................ 3810.2. Clock Sources............................................................................................................................ 3910.3. Low Frequency Crystal Oscillator...............................................................................................4110.4. Low Power Crystal Oscillator..................................................................................................... 4210.5. Calibrated Internal RC Oscillator................................................................................................4410.6. 128kHz Internal Oscillator.......................................................................................................... 45


10.7. External Clock............................................................................................................................ 4510.8. Timer/Counter Oscillator.............................................................................................................4610.9. Clock Output Buffer.................................................................................................................... 4710.10. System Clock Prescaler.............................................................................................................4710.11. Register Description...................................................................................................................47

11. CFD - Clock Failure Detection mechanism............................................................. 5011.1. Overview.................................................................................................................................... 5011.2. Features..................................................................................................................................... 5011.3. Operations..................................................................................................................................5011.4. Timing Diagram.......................................................................................................................... 5211.5. Register Description...................................................................................................................52

12. PM - Power Management and Sleep Modes...........................................................5312.1. Sleep Modes.............................................................................................................................. 5312.2. BOD Disable...............................................................................................................................5312.3. Idle Mode....................................................................................................................................5412.4. ADC Noise Reduction Mode...................................................................................................... 5412.5. Power-Down Mode.....................................................................................................................5512.6. Power-Save Mode......................................................................................................................5512.7. Standby Mode............................................................................................................................ 5612.8. Extended Standby Mode............................................................................................................5612.9. Power Reduction Registers........................................................................................................5612.10. Minimizing Power Consumption.................................................................................................5612.11. Register Description...................................................................................................................58

13. SCRST - System Control and Reset....................................................................... 6313.1. Resetting the AVR...................................................................................................................... 6313.2. Reset Sources............................................................................................................................6313.3. Power-on Reset..........................................................................................................................6413.4. External Reset............................................................................................................................6513.5. Brown-out Detection...................................................................................................................6513.6. Watchdog System Reset............................................................................................................6613.7. Internal Voltage Reference.........................................................................................................6613.8. Watchdog Timer......................................................................................................................... 6713.9. Register Description...................................................................................................................69

14. INT- Interrupts..........................................................................................................7314.1. Interrupt Vectors in ATmega324PB............................................................................................ 7314.2. Register Description...................................................................................................................76

15. External Interrupts................................................................................................... 7815.1. EXINT - External Interrupts........................................................................................................ 78

16. I/O-Ports.................................................................................................................. 8616.1. Overview.................................................................................................................................... 8616.2. Ports as General Digital I/O........................................................................................................8716.3. Alternate Port Functions.............................................................................................................9016.4. Register Description.................................................................................................................106

ATmega324PB


17. TC0 - 8-bit Timer/Counter0 with PWM...................................................................11417.1. Features................................................................................................................................... 11417.2. Overview...................................................................................................................................11417.3. Timer/Counter Clock Sources...................................................................................................11617.4. Counter Unit............................................................................................................................. 11617.5. Output Compare Unit................................................................................................................11717.6. Compare Match Output Unit.....................................................................................................11917.7. Modes of Operation..................................................................................................................12017.8. Timer/Counter Timing Diagrams.............................................................................................. 12417.9. Register Description.................................................................................................................126

18. TC1, 3, 4 - 16-bit Timer/Counter1, 3, 4 with PWM.................................................13418.1. Features................................................................................................................................... 13418.2. Overview.................................................................................................................................. 13418.3. Accessing 16-bit Timer/Counter Registers...............................................................................13518.4. Timer/Counter Clock Sources.................................................................................................. 13818.5. Counter Unit............................................................................................................................. 13818.6. Input Capture Unit.................................................................................................................... 13918.7. Compare Match Output Unit.....................................................................................................14118.8. Output Compare Units..............................................................................................................14218.9. Modes of Operation..................................................................................................................14418.10. Timer/Counter Timing Diagrams.............................................................................................. 15118.11. Register Description.................................................................................................................153

19. Timer/Counter 0, 1, 3, 4 Prescalers.......................................................................17919.1. Internal Clock Source...............................................................................................................17919.2. Prescaler Reset........................................................................................................................17919.3. External Clock Source..............................................................................................................17919.4. Register Description.................................................................................................................180

20. TC2 - 8-bit Timer/Counter2 with PWM and Asynchronous Operation...................18220.1. Features................................................................................................................................... 18220.2. Overview.................................................................................................................................. 18220.3. Timer/Counter Clock Sources.................................................................................................. 18420.4. Counter Unit............................................................................................................................. 18420.5. Output Compare Unit............................................................................................................... 18520.6. Compare Match Output Unit.....................................................................................................18720.7. Modes of Operation..................................................................................................................18820.8. Timer/Counter Timing Diagrams.............................................................................................. 19220.9. Asynchronous Operation of Timer/Counter2............................................................................19320.10. Timer/Counter Prescaler.......................................................................................................... 19520.11. Register Description.................................................................................................................195

21. OCM - Output Compare Modulator....................................................................... 20521.1. Overview.................................................................................................................................. 20521.2. Description............................................................................................................................... 205

22. SPI Serial Peripheral Interface........................................................................... 207

ATmega324PB


22.1. Features................................................................................................................................... 20722.2. Overview.................................................................................................................................. 20722.3. SS Pin Functionality................................................................................................................. 21122.4. Data Modes.............................................................................................................................. 21122.5. Register Description.................................................................................................................212

23. USART - Universal Synchronous Asynchronous Receiver Transceiver................21823.1. Features................................................................................................................................... 21823.2. Overview.................................................................................................................................. 21823.3. Block Diagram..........................................................................................................................21823.4. Clock Generation......................................................................................................................21923.5. Frame Formats.........................................................................................................................22223.6. USART Initialization................................................................................................................. 22323.7. Data Transmission The USART Transmitter......................................................................... 22423.8. Data Reception The USART Receiver.................................................................................. 22623.9. Asynchronous Data Reception.................................................................................................23023.10. Multi-Processor Communication Mode.................................................................................... 23423.11. Examples of Baud Rate Setting............................................................................................... 23423.12. Register Description.................................................................................................................237

24. USARTSPI - USART in SPI Mode.........................................................................24524.1. Features................................................................................................................................... 24524.2. Overview.................................................................................................................................. 24524.3. Clock Generation......................................................................................................................24524.4. SPI Data Modes and Timing.....................................................................................................24624.5. Frame Formats.........................................................................................................................24624.6. Data Transfer............................................................................................................................24824.7. AVR USART MSPIM vs. AVR SPI............................................................................................24924.8. Register Description.................................................................................................................250

25. TWI - 2-wire Serial Interface..................................................................................25125.1. Features................................................................................................................................... 25125.2. Two-Wire Serial Interface Bus Definition..................................................................................25125.3. Data Transfer and Frame Format.............................................................................................25225.4. Multi-master Bus Systems, Arbitration, and Synchronization...................................................25525.5. Overview of the TWI Module....................................................................................................25625.6. Using the TWI...........................................................................................................................25925.7. Transmission Modes................................................................................................................ 26225.8. Multi-master Systems and Arbitration...................................................................................... 27825.9. Register Description.................................................................................................................280

26. AC - Analog Comparator....................................................................................... 28526.1. Overview.................................................................................................................................. 28526.2. Analog Comparator Multiplexed Input......................................................................................28526.3. Register Description.................................................................................................................286

27. ADC - Analog to Digital Converter.........................................................................28927.1. Features................................................................................................................................... 28927.2. Overview.................................................................................................................................. 289

ATmega324PB


27.3. Starting a Conversion...............................................................................................................29127.4. Prescaling and Conversion Timing...........................................................................................29227.5. Changing Channel or Reference Selection..............................................................................29527.6. ADC Noise Canceler................................................................................................................ 29727.7. ADC Conversion Result........................................................................................................... 30127.8. Register Description.................................................................................................................303

28. PTC - Peripheral Touch Controller.........................................................................30928.1. Overview.................................................................................................................................. 30928.2. Features................................................................................................................................... 30928.3. Block Diagram..........................................................................................................................31028.4. Signal Description.................................................................................................................... 31028.5. System Dependencies............................................................................................................. 31028.6. Functional Description..............................................................................................................312

29. JTAG Interface and On-chip Debug System......................................................... 31329.1. Features................................................................................................................................... 31329.2. Overview.................................................................................................................................. 31329.3. TAP Test Access Port............................................................................................................31429.4. TAP Controller.......................................................................................................................... 31529.5. Using the Boundary-scan Chain...............................................................................................31629.6. Using the On-chip Debug System............................................................................................31629.7. On-chip Debug Specific JTAG Instructions.............................................................................. 31729.8. Using the JTAG Programming Capabilities.............................................................................. 31729.9. Bibliography..............................................................................................................................31829.10. IEEE 1149.1 (JTAG) Boundary-scan........................................................................................31829.11. Data Registers..........................................................................................................................31929.12. Boundry-scan Specific JTAG Instructions................................................................................32029.13. Boundary-scan Chain...............................................................................................................32229.14. ATmega324PB Boundary-scan Order......................................................................................32529.15. Boundary-scan Description Language Files............................................................................ 32729.16. Register Description.................................................................................................................327

30. BTLDR - Boot Loader Support Read-While-Write Self-Programming................ 33130.1. Features................................................................................................................................... 33130.2. Overview.................................................................................................................................. 33130.3. Application and Boot Loader Flash Sections............................................................................33130.4. Read-While-Write and No Read-While-Write Flash Sections...................................................33230.5. Entering the Boot Loader Program...........................................................................................33430.6. Boot Loader Lock Bits.............................................................................................................. 33530.7. Addressing the Flash During Self-Programming......................................................................33630.8. Self-Programming the Flash.....................................................................................................33730.9. Register Description.................................................................................................................345

31. MEMPROG- Memory Programming......................................................................34731.1. Program And Data Memory Lock Bits......................................................................................34731.2. Fuse Bits.................................................................................................................................. 34831.3. Signature Bytes........................................................................................................................35031.4. Calibration Byte........................................................................................................................350

ATmega324PB


31.5. Serial Number.......................................................................................................................... 35131.6. Page Size.................................................................................................................................35331.7. Parallel Programming Parameters, Pin Mapping, and Commands..........................................35431.8. Parallel Programming...............................................................................................................35631.9. Serial Downloading.................................................................................................................. 36331.10. Programming Via the JTAG Interface...................................................................................... 368

32. Electrical Characteristics....................................................................................... 38332.1. Absolute Maximum Ratings......................................................................................................38332.2. DC Characteristics................................................................................................................... 38332.3. Speed Grades.......................................................................................................................... 38532.4. Clock Characteristics................................................................................................................38632.5. System and Reset Characteristics........................................................................................... 38732.6. SPI Timing Characteristics....................................................................................................... 38832.7. Two-wire Serial Interface Characteristics.................................................................................38932.8. ADC Characteristics.................................................................................................................39132.9. Parallel Programming Characteristics......................................................................................394

33. Typical Characteristics...........................................................................................39733.1. Active Supply Current...............................................................................................................39733.2. Idle Supply Current...................................................................................................................40133.3. Supply Current of IO Modules .................................................................................................40333.4. Power-down Supply Current.................................................................................................... 40433.5. Pin Pull-Up............................................................................................................................... 40633.6. Pin Driver Strength...................................................................................................................40933.7. Pin Threshold and Hysteresis...................................................................................................41133.8. BOD Threshold.........................................................................................................................41433.9. Analog Comparator Offset........................................................................................................41733.10. Internal Oscillator Speed..........................................................................................................41833.11. Current Consumption of Peripheral Units.................................................................................42133.12. Current Consumption in Reset and Reset Pulse Width........................................................... 424

34. Register Summary.................................................................................................426

35. Instruction Set Summary....................................................................................... 431

36. Packaging Information...........................................................................................43536.1. 44-pin TQFP.............................................................................................................................43536.2. 44-pin VQFN............................................................................................................................ 436

37. Errata.....................................................................................................................43737.1. Rev.A-H.................................................................................................................................... 43737.2. Rev. I........................................................................................................................................ 43737.3. Rev. J - K..................................................................................................................................437

38. Datasheet Revision History................................................................................... 438

The Microchip Web Site.............................................................................................. 440

Customer Change Notification Service........................................................................440

ATmega324PB


Customer Support....................................................................................................... 440

Microchip Devices Code Protection Feature............................................................... 440

Legal Notice.................................................................................................................441

Trademarks................................................................................................................. 441

Quality Management System Certified by DNV...........................................................442

Worldwide Sales and Service......................................................................................443

ATmega324PB


1. DescriptionThe ATmega324PB is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISCarchitecture. By executing powerful instructions in a single clock cycle, the ATmega324PB achievesthroughputs close to 1MIPS per MHz. This empowers system designers to optimize the device for powerconsumption versus processing speed.

The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers tobe accessed in a single instruction executed in one clock cycle. The resulting architecture is more codeefficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.

The ATmega324PB provides the following features: 32K bytes of In-System Programmable Flash withRead-While-Write capabilities, 1Kbytes EEPROM, 2Kbytes SRAM, 39 general purpose I/O lines, 32general purpose working registers, five flexible Timer/Counters with compare modes, internal andexternal interrupts, three serial programmable USART, two byte-oriented 2-wire Serial Interface (I2C), twoSPI serial port, a 8-channel 10-bit ADC with optional differential input stage with programmable gain, aprogrammable Watchdog Timer with internal Oscillator, IEEE std. 1149.1 compliant JTAG test interface,also used for accessing the On-chip Debug system and programming, Clock failure detection mechanismand six software selectable power saving modes. The Idle mode stops the CPU while allowing the SRAM,Timer/Counters, USART, 2-wire Serial Interface, SPI port, and interrupt system to continue functioning.PTC with enabling up to 32 self-cap and 256 mutual-cap sensors. The Power-down mode saves theregister contents but freezes the Oscillator, disabling all other chip functions until the next interrupt orhardware reset. In Power-save mode, the asynchronous timer continues to run, allowing the user tomaintain a timer base while the rest of the device is sleeping. Also ability to run PTC in power-save mode/wake-up on touch and Dynamic on/off of PTC analog and digital portion. The ADC Noise Reduction modestops the CPU and all I/O modules except asynchronous timer, PTC, and ADC to minimize switchingnoise during ADC conversions. In Standby mode, the crystal/resonator Oscillator is running while the restof the device is sleeping. This allows very fast start-up combined with low power consumption.

The device is manufactured using high density non-volatile memory technology. The On-chip ISP Flashallows the program memory to be reprogrammed In-System through an SPI serial interface, by aconventional nonvolatile memory programmer, or by an On-chip Boot program running on the AVR core.The Boot program can use any interface to download the application program in the Application Flashmemory. Software in the Boot Flash section will continue to run while the Application Flash section isupdated, providing true Read-While-Write operation. By combining an 8-bit RISC CPU with In-SystemSelf-Programmable Flash on a monolithic chip, the ATmega324PB is a powerful microcontroller thatprovides a highly flexible and cost effective solution to many embedded control applications.

The ATmega324PB is supported with a full suite of program and system development tools including: CCompilers, Macro Assemblers, Program Debugger/Simulators, In-Circuit Emulators, and Evaluation kits.

ATmega324PB


2. Configuration SummaryFeatures ATmega324PB

Pin count 44

Flash (KB) 32

SRAM (KB) 2

EEPROM (KB) 1

General Purpose I/O lines 39

SPI 2

TWI (I2C) 2

USART 3

ADC 10-bit 15ksps

Differential ADC mode Available

ADC channels 8

AC 1

8-bit Timer/Counters 2

16-bit Timer/Counters 3

PWM channels 10

PTC Available

Peripheral Touch Controller (PTC) channels (X- x Y-Lines) for mutual capacitance 256 (16 x 16)

Peripheral Touch Controller (PTC) channels for self capacitance (Y-Lines only) 32

Clock Failure Detector (CFD) Available

Output Compare Modulator (OCM1C2) Available

ATmega324PB


3. Ordering InformationSpeed [MHz] Power Supply [V] Ordering Code(2) Package(1) Operational Range

20 1.8 - 5.5 ATmega324PB-AUATmega324PB-AUR(3)ATmega324PB-MUATmega324PB-MUR(3)

44A44A44M144M1

Industrial(-40C to 85C)

ATmega324PB-ANATmega324PB-ANR(3)ATmega324PB-MNATmega324PB-MNR(3)

44A44A44M144M1

Industrial(-40C to 105C)

Note: 1. This device can also be supplied in wafer form. Contact your local sales office for detailedordering information and minimum quantities.

2. Pb-free packaging complies to the European Directive for Restriction of Hazardous Substances (RoHSdirective). Also Halide free and fully Green.

3. Tape & Reel.

Package Type

44A 44-lead, Thin (1.0mm) Plastic Quad Flat Package (TQFP)

44M1 44-pad, 7 x 7 x 0.9mm body, Lead Pitch 0.50mm, Very-thin Fine pitch, Quad Flat No Lead Package/QuadFlat No-Lead/Micro Lead Frame Package (VQFN/QFN/MLF)

ATmega324PB


4. Block DiagramFigure 4-1.Block Diagram

CPU

USART 0

ADCADC[7:0]AREF

RxD0TxD0XCK0

I/OPORTS

DATABUS

GPIOR[2:0]

SRAM

OCD

EXTINT

FLASHNVM

programming

JTAG

IN/OUT

DATABUS

TC 0(8-bit)

SPI 0

ACAIN0AIN1ACOADCMUX

EEPROM

EEPROMIF

PTCX[15:0]Y[31:0]

TC 1(16-bit)

OC1A/BT1

ICP1

TC 3(16-bit)

TC 4(16-bit)

OC3A/BT3

ICP3

OC4A/BT4

ICP4

TC 2 (8-bit async)

TWI 0

TWI 1

SDA0SCL0

SDA1SCL1

USART 1

USART 2

RxD1TxD1XCK1

RxD2TxD2XCK2

InternalReference

Watchdog Timer

Power management

and clock control

VCC

GND

Clock generation8MHz

Calib RC

128kHz int osc

32.768kHz XOSC

External clock

Power SupervisionPOR/BOD &

RESET

TOSC2

XTAL2

RESET

XTAL1

TOSC1

16MHz LP XOSC

TCKTMSTDI

TDO

Crystal failure detection

PCINT[38:0]INT[2:0]

T0OC0AOC0B

MISO0MOSI0SCK0SS0

OC2AOC2B

PA[7:0]PB[7:0]PC[7:0]PD[7:0]PE[6:0]

SPI 1MISO1MOSI1SCK1SS1

ATmega324PB


5. Pin ConfigurationsFigure 5-1.Pinout ATmega324PB

Power

Ground

Programming/debug

Digital

Analog

Crystal/Osc

1

2

3

4

43 42 41 40 39 38 37

5

6

7

8

35 34222120191817

369

10

11

12 13 14 15 16

AVCC

RESET

GND

VCC

(XTAL1) PE1

(XTAL2) PE0

PC7 (TOSC2)

PE4 (AREF)

GND

PB0

(PTC

Y/T0

/XC

K0)

PB1

(PTC

Y/T1

/CLK

O)

PB2

(AIN

0/PT

CY/

INT2

)

(MOSI0/ICP3/PTCY) PB5

(MISO0/OC3A/PTCY) PB6

44

32

31

30

29

28

27

26

24

23

25

33

(SCK0/OC3B/OC4B/PTCY) PB7

PB3

(AIN

1/PT

CY/

OC

0A)

PB4

(PTC

Y/O

C0B

/SS0

)

PE5

(SD

A1)

PE6

(SC

L1)

PA0

(AD

C0/

PTC

Y)

PA1

(AD

C1/

PTC

Y)

PA2

(AD

C2/

PTC

Y)

PA3

(AD

C3/

PTC

Y)

PA4 (ADC4/PTCY)

PA5 (ADC5/PTCY)

PA6 (ADC6/PTCY)

PA7 (ADC7/PTCY)

PC6 (TOSC1)

PC4 (PTCXY/OC4A/TDO)

PC5 (PTCXY/ACO/TDI)

(TM

S/IC

P4/P

TCXY

) PC

3

(TC

K/T4

/PTC

XY) P

C2

(SD

A0/P

TCXY

) PC

1

(SC

L0/P

TCXY

) PC

0

(MO

SI1/

TXD

2/PT

CXY

) PE3

(MIS

O1/

RXD

2/PT

CXY

) PE2

(SC

K1/X

CK2

/OC

2A/P

TCXY

) PD

7

(SS1

/ICP1

/OC

2B/P

TCXY

) PD

6

(OC

1A/P

TCXY

) PD

5

(XC

K1/O

C1B

/PTC

XY) P

D4

(TXD

1/IN

T1/P

TCXY

) PD

3

(RXD1/INT0/PTCXY) PD2

(TXD0/PTCXY) PD1

(RXD0/T3/PTCXY) PD0

5.1 Pin Descriptions

5.1.1 VCCDigital supply voltage.

5.1.2 GNDGround.

ATmega324PB


5.1.3 Port A (PA[7:0])This port serves as analog inputs to the Analog-to-digital Converter.

This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each pin.The output buffers have symmetrical drive characteristics, with both high sink and source capability. Asinputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Portpins are tri-stated during a reset condition, even if the clock is not running.

5.1.4 Port B (PB[7:0])This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each pin.The output buffers have symmetrical drive characteristics, with both high sink and source capability. Asinputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Portpins are tri-stated during a reset condition, even if the clock is not running.

This port also serves the functions of various special features.

5.1.5 Port C (PC[7:0])This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each pin.The output buffers have symmetrical drive characteristics, with both high sink and source capability. Asinputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Portpins are tri-stated during a reset condition, even if the clock is not running.

This port also serves the functions of the JTAG interface, along with special features.

5.1.6 Port D (PD[7:0])This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each pin.The output buffers have symmetrical drive characteristics, with both high sink and source capability. Asinputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Portpins are tri-stated during a reset condition, even if the clock is not running.

This port also serves the functions of various special features.

5.1.7 Port E (PE6:0) XTAL1/XTAL2/AREFThis is a 7-bit bi-directional GPIO port with internal pull-up resistors (selected for each pin). The Port Eoutput buffers have symmetrical drive characteristics with both high sink and source capability. As inputs,Port E pins that are externally pulled low will source current if the pull-up resistors are activated. Port pinsare tri-stated during a reset condition, even if the clock is not running. PE0 and PE1 are multiplexed withXTAL1 and XTAL2 input. PE4 is multiplexed with AREF for the A/D Converter.

5.1.8 RESETReset input. A low level on this pin for longer than the minimum pulse length will generate a reset, even ifthe clock is not running. Shorter pulses are not guaranteed to generate a reset.

5.1.9 AVCCAVCC is the supply voltage pin for Port A, PE4 (AREF) and the Analog-to-digital Converter. It should beexternally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected toVCC through a low-pass filter.

ATmega324PB


6. I/O MultiplexingEach pin is by default controlled by the PORT as a general purpose I/O and alternatively it can beassigned to one of the peripheral functions.

The following table describes the peripheral signals multiplexed to the PORT I/O pins.

Table 6-1.PORT Function Multiplexing

No. PAD EXTINT PCINT ADC/AC PTC X PTC Y OSC T/C # 0 T/C # 1 USART I2C SPI JTAG

1 PB[5] PCINT13 Y29 ICP3 MOSI0

2 PB[6] PCINT14 Y30 OC3A MISO0

3 PB[7] PCINT15 Y31 OC3B OC4B SCK0

4 RESET

5 VCC

6 GND

7 PE[0] PCINT32 XTAL2

8 PE[1] PCINT33 XTAL1

9 PD[0] PCINT24 X0 Y8 T3 RxD0

10 PD[1] PCINT25 X1 Y9 TxD0

11 PD[2] INT0 PCINT26 X2 Y10 RxD1

12 PD[3] INT1 PCINT27 X3 Y11 TXD1

13 PD[4] PCINT28 X4 Y12 OC1B XCK1

14 PD[5] PCINT29 X5 Y13 OC1A

15 PD[6] PCINT30 X6 Y14 OC2B ICP1 SS1

16 PD[7] PCINT31 X7 Y15 OC2A XCK2 SCK1

17 PE[2] X8 Y16 RxD2 MISO1

18 PE[3] X9 Y17 TxD2 MOSI1

19 PC[0] PCINT16 X10 Y18 SCL0

20 PC[1] PCINT17 X11 Y19 SDA0

21 PC[2] PCINT18 X12 Y20 T4 TCK

22 PC[3] PCINT19 X13 Y21 ICP4 TMS

23 PC[4] PCINT20 X14 Y22 OC4A TDO

24 PC[5] PCINT21 ACO X15 Y23 TDI

25 PC[6] PCINT22 TOSC1

26 PC[7] PCINT23 TOSC2

27 AVCC

28 GND

29 PE[4] AREF

30 PA[7] PCINT7 ADC7 Y7





ATmega324PB


No. PAD EXTINT PCINT ADC/AC PTC X PTC Y OSC T/C # 0 T/C # 1 USART I2C SPI JTAG




38 PE[5] SDA1

39 PE[6] SCL1

40 PB[0] PCINT8 Y24 T0 XCK0

41 PB[1] PCINT9 Y25 CLKO T1

42 PB[2] INT2 PCINT10 AIN0 Y26

43 PB[3] PCINT11 AIN1 Y27 OC0A

44 PB[4] PCINT12 Y28 OC0B SS0

ATmega324PB


7. General Information

7.1 ResourcesA comprehensive set of development tools, application notes, and datasheets are available for downloadon http://www.microchip.com/design-centers/8-bit/microchip-avr-mcus.

7.2 About Code ExamplesThis documentation contains simple code examples that briefly show how to use various parts of thedevice. These code examples assume that the part specific header file is included before compilation. Beaware that not all C compiler vendors include bit definitions in the header files and interrupt handling in Cis compiler dependent. Confer with the C compiler documentation for more details.

For I/O Registers located in extended I/O map, IN, OUT, SBIS, SBIC, CBI, and SBI instructionsmust be replaced with instructions that allow access to extended I/O. Typically LDS and STScombined with SBRS, SBRC, SBR, and CBR.

ATmega324PB


http://www.microchip.com/design-centers/8-bit/microchip-avr-mcus

8. AVR CPU Core

8.1 OverviewThis section discusses the AVR core architecture in general. The main function of the CPU core is toensure correct program execution. The CPU must therefore be able to access memories, performcalculations, control peripherals, and handle interrupts.

Figure 8-1.Block Diagram of the AVR Architecture

Register file

Flash program memory

Program counter

Instruction register

Instruction decode

Data memory

ALUStatus register

R0R1R2R3R4R5R6R7R8R9

R10R11R12R13R14R15R16R17R18R19R20R21R22R23R24R25

R26 (XL)R27 (XH)R28 (YL)R29 (YH)R30 (ZL)R31 (ZH)

Stack pointer

In order to maximize performance and parallelism, the AVR uses a Harvard architecture with separatememories and buses for program and data. Instructions in the program memory are executed with asingle level pipelining. While one instruction is being executed, the next instruction is pre-fetched from theprogram memory. This concept enables instructions to be executed in every clock cycle. The programmemory is In-System Reprogrammable Flash memory.

The fast-access Register File contains 32 x 8-bit general purpose working registers with a single clockcycle access time. This allows single-cycle Arithmetic Logic Unit (ALU) operation. In a typical ALUoperation, two operands are output from the Register File, the operation is executed, and the result isstored back in the Register File in one clock cycle.

Six of the 32 registers can be used as three 16-bit indirect address register pointers for Data Spaceaddressing enabling efficient address calculations. One of the these address pointers can also be usedas an address pointer for look up tables in Flash program memory. These added function registers arethe 16-bit X-, Y-, and Z-register, described later in this section.

ATmega324PB


The ALU supports arithmetic and logic operations between registers or between a constant and aregister. Single register operations can also be executed in the ALU. After an arithmetic operation, theStatus Register is updated to reflect information about the result of the operation.

Program flow is provided by conditional and unconditional jump and call instructions, able to directlyaddress the whole address space. Most AVR instructions have a single 16-bit word format. Everyprogram memory address contains a 16- or 32-bit instruction.

Program Flash memory space is divided in two sections, the Boot Program section and the ApplicationProgram section. Both sections have dedicated Lock bits for write and read/write protection. The SPMinstruction that writes into the Application Flash memory section must reside in the Boot Program section.

During interrupts and subroutine calls, the return address Program Counter (PC) is stored on the Stack.The Stack is effectively allocated in the general data SRAM, and consequently the Stack size is onlylimited by the total SRAM size and the usage of the SRAM. All user programs must initialize the SP in theReset routine (before subroutines or interrupts are executed). The Stack Pointer (SP) is read/writeaccessible in the I/O space. The data SRAM can easily be accessed through the five different addressingmodes supported in the AVR architecture.

The memory spaces in the AVR architecture are all linear and regular memory maps.

A flexible interrupt module has its control registers in the I/O space with an additional Global InterruptEnable bit in the Status Register. All interrupts have a separate Interrupt Vector in the Interrupt Vectortable. The interrupts have priority in accordance with their Interrupt Vector position. The lower theInterrupt Vector address, the higher the priority.

The I/O memory space contains 64 addresses for CPU peripheral functions as Control Registers, SPI,and other I/O functions. The I/O Memory can be accessed directly, or as the Data Space locationsfollowing those of the Register File, 0x20 - 0x5F. In addition, this device has Extended I/O space from0x60 - 0xFF in SRAM where only the ST/STS/STD and LD/LDS/LDD instructions can be used.

8.2 ALU Arithmetic Logic UnitThe high-performance AVR ALU operates in direct connection with all the 32 general purpose workingregisters. Within a single clock cycle, arithmetic operations between general purpose registers orbetween a register and an immediate are executed. The ALU operations are divided into three maincategories arithmetic, logical, and bit-functions. Some implementations of the architecture also providea powerful multiplier supporting both signed/unsigned multiplication and fractional format. See InstructionSet Summary section for a detailed description.

Related LinksInstruction Set Summary

8.3 Status RegisterThe Status Register contains information about the result of the most recently executed arithmeticinstruction. This information can be used for altering program flow in order to perform conditionaloperations. The Status Register is updated after all ALU operations, as specified in the Instruction SetReference. This will in many cases remove the need for using the dedicated compare instructions,resulting in faster and more compact code.

The Status Register is not automatically stored when entering an interrupt routine and restored whenreturning from an interrupt. This must be handled by software.

ATmega324PB


8.3.1 Status Register

When addressing I/O Registers as data space using LD and ST instructions, the provided offset must beused. When using the I/O specific commands IN and OUT, the offset is reduced by 0x20, resulting in anI/O address offset within 0x00 - 0x3F.

Name: SREGOffset: 0x5FReset: 0x00Property:

When addressing as I/O Register: address offset is 0x3F

Bit 7 6 5 4 3 2 1 0 I T H S V N Z C

Access R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0

Bit 7 I:Global Interrupt EnableThe Global Interrupt Enable bit must be set for interrupts to be enabled. The individual interrupt enablecontrol is then performed in separate control registers. If the Global Interrupt Enable Register is cleared,none of the interrupts are enabled independent of the individual interrupt enable settings. The I-bit iscleared by hardware after an interrupt has occurred, and is set by the RETI instruction to enablesubsequent interrupts. The I-bit can also be set and cleared by the application with the SEI and CLIinstructions, as described in the instruction set reference.

Bit 6 T:Copy StorageThe Bit Copy instructions BLD (Bit LoaD) and BST (Bit STore) use the T-bit as source or destination forthe operated bit. A bit from a register in the Register File can be copied into T by the BST instruction, anda bit in T can be copied into a bit in a register in the Register File by the BLD instruction.

Bit 5 H:Half Carry FlagThe Half Carry Flag H indicates a Half Carry in some arithmetic operations. Half Carry Flag is useful inBCD arithmetic. See the Instruction Set Description for detailed information.

Bit 4 S:Sign Flag, S = N V

The S-bit is always an exclusive or between the Negative Flag N and the Twos Complement OverflowFlag V. See the Instruction Set Description for detailed information.

Bit 3 V:Twos Complement Overflow FlagThe Twos Complement Overflow Flag V supports twos complement arithmetic. See the Instruction SetDescription for detailed information.

Bit 2 N:Negative FlagThe Negative Flag N indicates a negative result in an arithmetic or logic operation. See the Instruction SetDescription for detailed information.

Bit 1 Z:Zero FlagThe Zero Flag Z indicates a zero result in an arithmetic or logic operation. See the Instruction SetDescription for detailed information.

ATmega324PB


Bit 0 C:Carry FlagThe Carry Flag C indicates a carry in an arithmetic or logic operation. See the Instruction Set Descriptionfor detailed information.

8.4 General Purpose Register FileThe Register File is optimized for the AVR Enhanced RISC instruction set. In order to achieve therequired performance and flexibility, the following input/output schemes are supported by the RegisterFile:

One 8-bit output operand and one 8-bit result input Two 8-bit output operands and one 8-bit result input Two 8-bit output operands and one 16-bit result input One 16-bit output operand and one 16-bit result input

Figure 8-2.AVR CPU General Purpose Working Registers

7 0 Addr.

R0 0x00

R1 0x01

R2 0x02

R13 0x0D

General R14 0x0E

Purpose R15 0x0F

Working R16 0x10

Registers R17 0x11

R26 0x1A X-register Low Byte

R27 0x1B X-register High Byte

R28 0x1C Y-register Low Byte

R29 0x1D Y-register High Byte

R30 0x1E Z-register Low Byte

R31 0x1F Z-register High Byte

Most of the instructions operating on the Register File have direct access to all registers, and most ofthem are single cycle instructions. As shown in the figure, each register is also assigned a data memoryaddress, mapping them directly into the first 32 locations of the user Data Space. Although not beingphysically implemented as SRAM locations, this memory organization provides great flexibility in accessof the registers, as the X-, Y-, and Z-pointer registers can be set to index any register in the file.

8.4.1 The X-register, Y-register, and Z-registerThe registers R26...R31 have some added functions to their general purpose usage. These registers are16-bit address pointers for indirect addressing of the data space. The three indirect address registers X,Y, and Z are defined as described in the figure.

Figure 8-3.The X-, Y-, and Z-registers15 XH XL 0

X-register 7 0 7 0

R27 R26

15 YH YL 0

Y-register 7 0 7 0

R29 R28

15 ZH ZL 0

Z-register 7 0 7 0

R31 R30

In the different addressing modes these address registers have functions as fixed displacement,automatic increment, and automatic decrement (see the instruction set reference for details).

Related LinksInstruction Set Summary

ATmega324PB


8.5 Stack PointerThe Stack is mainly used for storing temporary data, for storing local variables and for storing returnaddresses after interrupts and subroutine calls. The Stack is implemented as growing from higher tolower memory locations. The Stack Pointer Register always points to the top of the Stack.

The Stack Pointer points to the data SRAM Stack area where the Subroutine and Interrupt Stacks arelocated. A Stack PUSH command will decrease the Stack Pointer. The Stack in the data SRAM must bedefined by the program before any subroutine calls are executed or interrupts are enabled. Initial StackPointer value equals the last address of the internal SRAM and the Stack Pointer must be set to pointabove start of the SRAM. See the table for Stack Pointer details.

Table 8-1.Stack Pointer Instructions

Instruction Stack pointer Description

PUSH Decremented by 1 Data is pushed onto the stack

CALL

ICALL

RCALL

Decremented by 2 Return address is pushed onto the stack with a subroutine call orinterrupt

POP Incremented by 1 Data is popped from the stack

RET

RETI

Incremented by 2 Return address is popped from the stack with return from subroutine orreturn from interrupt

The AVR Stack Pointer is implemented as two 8-bit registers in the I/O space. The number of bits actuallyused is implementation dependent. Note that the data space in some implementations of the AVRarchitecture is so small that only SPL is needed. In this case, the SPH Register will not be present.

8.5.1 Stack Pointer Register Low and High byte

The SPL and SPH register pair represents the 16-bit value, SP.The low byte [7:0] (suffix L) is accessibleat the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01. For more details onreading and writing 16-bit registers, refer to Accessing 16-bit Registers.

When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. Whenaddressing I/O Registers as data space using LD and ST instructions, 0x20 must be added to these offsetaddresses.

Name: SPL and SPHOffset: 0x5DReset: 0x8FFProperty:

When addressing I/O Registers as data space the offset address is 0x3D

ATmega324PB


Bit 15 14 13 12 11 10 9 8 SP[11:8]

Access R R R R RW RW RW RW Reset 0 0 0 0 1 0 0 0

Bit 7 6 5 4 3 2 1 0 SP[7:0]

Access RW RW RW RW RW RW RW RW Reset 1 1 1 1 1 1 1 1

Bits 11:0 SP[11:0]:Stack Pointer RegisterSPL and SPH are combined into SP.

8.6 Accessing 16-bit RegistersThe AVR data bus is 8 bits wide, and so accessing 16-bit registers requires atomic operations. Theseregisters must be byte-accessed using two read or write operations. 16-bit registers are connected to the8-bit bus and a temporary register using a 16-bit bus.

For a write operation, the low byte of the 16-bit register must be written before the high byte. The low byteis then written into the temporary register. When the high byte of the 16-bit register is written, thetemporary register is copied into the low byte of the 16-bit register in the same clock cycle.

For a read operation, the low byte of the 16-bit register must be read before the high byte. When the lowbyte register is read by the CPU, the high byte of the 16-bit register is copied into the temporary registerin the same clock cycle as the low byte is read. When the high byte is read, it is then read from thetemporary register.

This ensures that the low and high bytes of 16-bit registers are always accessed simultaneously whenreading or writing the register.

Interrupts can corrupt the timed sequence if an interrupt is triggered and accesses the same 16-bitregister during an atomic 16-bit read/write operation. To prevent this, interrupts can be disabled whenwriting or reading 16-bit registers.

The temporary registers can also be read and written directly from user software.

8.7 Instruction Execution TimingThis section describes the general access timing concepts for instruction execution. The AVR CPU isdriven by the CPU clock clkCPU, directly generated from the selected clock source for the chip. No internalclock division is used. The Figure below shows the parallel instruction fetches and instruction executionsenabled by the Harvard architecture and the fast-access Register File concept. This is the basicpipelining concept to obtain up to 1 MIPS per MHz with the corresponding unique results for functions percost, functions per clocks, and functions per power-unit.

ATmega324PB


Figure 8-4.The Parallel Instruction Fetches and Instruction Executions

clk

1st Instruction Fetch1st Instruction Execute

2nd Instruction Fetch2nd Instruction Execute

3rd Instruction Fetch3rd Instruction Execute

4th Instruction Fetch

T1 T2 T3 T4

CPU

The following figure shows the internal timing concept for the Register File. In a single clock cycle an ALUoperation using two register operands is executed, and the result is stored back to the destinationregister.

Figure 8-5.Single Cycle ALU Operation

Total Execution Time

Register Operands Fetch

ALU Operation Execute

Result Write Back

T1 T2 T3 T4

clkCPU

8.8 Reset and Interrupt HandlingThe AVR provides several different interrupt sources. These interrupts and the separate Reset Vectoreach have a separate program vector in the program memory space. All interrupts are assignedindividual enable bits which must be written logic one together with the Global Interrupt Enable bit in theStatus Register in order to enable the interrupt. Depending on the Program Counter value, interrupts maybe automatically disabled when Boot Lock bits BLB02 or BLB12 are programmed. This feature improvessoftware security.

The lowest addresses in the program memory space are by default defined as the Reset and InterruptVectors. They have determined priority levels: The lower the address the higher is the priority level.RESET has the highest priority, and next is INT0 the External Interrupt Request 0. The Interrupt Vectorscan be moved to the start of the Boot Flash section by setting the IVSEL bit in the MCU Control Register(MCUCR). The Reset Vector can also be moved to the start of the Boot Flash section by programmingthe BOOTRST Fuse.

When an interrupt occurs, the Global Interrupt Enable I-bit is cleared and all interrupts are disabled. Theuser software can write logic one to the I-bit to enable nested interrupts. All enabled interrupts can theninterrupt the current interrupt routine. The I-bit is automatically set when a Return from Interruptinstruction RETI is executed.

There are basically two types of interrupts:

The first type is triggered by an event that sets the Interrupt Flag. For these interrupts, the ProgramCounter is vectored to the actual Interrupt Vector in order to execute the interrupt handling routine, and

ATmega324PB


hardware clears the corresponding Interrupt Flag. Interrupt Flags can also be cleared by writing a logicone to the flag bit position(s) to be cleared. If an interrupt condition occurs while the correspondinginterrupt enable bit is cleared, the Interrupt Flag will be set and remembered until the interrupt is enabled,or the flag is cleared by software. Similarly, if one or more interrupt conditions occur while the GlobalInterrupt Enable bit is cleared, the corresponding Interrupt Flag(s) will be set and remembered until theGlobal Interrupt Enable bit is set, and will then be executed by order of priority.

The second type of interrupts will trigger as long as the interrupt condition is present. These interrupts donot necessarily have Interrupt Flags. If the interrupt condition disappears before the interrupt is enabled,the interrupt will not be triggered. When the AVR exits from an interrupt, it will always return to the mainprogram and execute one more instruction before any pending interrupt is served.

The Status Register is not automatically stored when entering an interrupt routine, nor restored whenreturning from an interrupt routine. This must be handled by software.

When using the CLI instruction to disable interrupts, the interrupts will be immediately disabled. Nointerrupt will be executed after the CLI instruction, even if it occurs simultaneously with the CLIinstruction. The following example shows how this can be used to avoid interrupts during the timedEEPROM write sequence.

Assembly Code Example(1)

in r16, SREG ; store SREG valuecli ; disable interrupts during timed sequencesbi EECR, EEMPE ; start EEPROM writesbi EECR, EEPEout SREG, r16 ; restore SREG value (I-bit)

C Code Example(1)

char cSREG;cSREG = SREG; /* store SREG value *//* disable interrupts during timed sequence */_CLI();EECR |= (1

8.8.1 Interrupt Response TimeThe interrupt execution response for all the enabled AVR interrupts is four clock cycles minimum. Afterfour clock cycles the program vector address for the actual interrupt handling routine is executed. Duringthis four clock cycle period, the Program Counter is pushed onto the Stack. The vector is normally a jumpto the interrupt routine, and this jump takes three clock cycles. If an interrupt occurs during execution of amulti-cycle instruction, this instruction is completed before the interrupt is served. If an interrupt occurswhen the MCU is in sleep mode, the interrupt execution response time is increased by four clock cycles.This increase comes in addition to the start-up time from the selected sleep mode. A return from aninterrupt handling routine takes four clock cycles. During these four clock cycles, the Program Counter(two bytes) is popped back from the Stack, the Stack Pointer is incremented by two, and the I-bit inSREG is set.

ATmega324PB


9. AVR Memories

9.1 OverviewThis section describes the different memory types in the device. The AVR architecture has two mainmemory spaces, the Data Memory and the Program Memory space. In addition, the device features anEEPROM Memory for data storage. All memory spaces are linear and regular.

9.2 In-System Reprogrammable Flash Program MemoryThe ATmega324PB contains 32K bytes on-chip in-system reprogrammable Flash memory for programstorage. Since all AVR instructions are 16 or 32 bits wide, the Flash is organized as 32K x 16. Forsoftware security, the Flash Program memory space is divided into two sections - Boot Loader Sectionand Application Program Section in the device .

The Flash memory has an endurance of at least 10,000 write/erase cycles. The ATmega324PB ProgramCounter (PC) is 15 bits wide, thus addressing the 32K program memory locations. The operation of theBoot Program section and associated Boot Lock bits for software protection are described in detail inBoot Loader Support Read-While-Write Self-Programming. Refer to Memory Programming for thedescription on Flash data serial downloading using the SPI pins or the JTAG interface.

Constant tables can be allocated within the entire program memory address space, using the LoadProgram Memory (LPM) instruction.

Timing diagrams for instruction fetch and execution are presented in Instruction Execution Timing.

Figure 9-1.Program Memory Map ATmega324PB

0x0000

0x3FFF

Program Memory

Application Flash Section

Boot Flash Section

Related LinksBTLDR - Boot Loader Support Read-While-Write Self-ProgrammingMEMPROG- Memory ProgrammingInstruction Execution Timing

ATmega324PB


9.3 SRAM Data MemoryThe following figure shows how the device SRAM Memory is organized.

The device is a complex microcontroller with more peripheral units than can be supported within the 64locations reserved in the Opcode for the IN and OUT instructions. For the Extended I/O space from 0x60- 0xFF in SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used.

The lower 4352 data memory locations address both the Register File, the I/O memory, Extended I/Omemory, and the internal data SRAM. The first 32 locations address the Register File, the next 64location the standard I/O memory, then 160 locations of Extended I/O memory, and the next 4096locations address the internal data SRAM.

The five different addressing modes for the data memory cover: Direct

The direct addressing reaches the entire data space. Indirect with Displacement

The Indirect with Displacement mode reaches 63 address locations from the base addressgiven by the Y- or Z-register.

Indirect In the Register File, registers R26 to R31 feature the indirect addressing pointer registers.

Indirect with Pre-decrement The address registers X, Y, and Z are decremented.

Indirect with Post-increment The address registers X, Y, and Z are incremented.

The 32 general purpose working registers, 64 I/O Registers, 160 Extended I/O Registers, and the 2Kbytes of internal data SRAM in the device are all accessible through all these addressing modes.

Figure 9-2.Data Memory Map with 2048 byte internal data SRAM

(2048x8)

0x08FF9.3.1 Data Memory Access Times

The internal data SRAM access is performed in two clkCPU cycles as described in the following Figure.

ATmega324PB


Figure 9-3.On-chip Data SRAM Access Cycles

clk

WR

RD

Data

Data

Address Address valid

T1 T2 T3

Compute Address

Rea

dW

rite

CPU

Memory Access Instruction Next Instruction

9.4 EEPROM Data MemoryThe ATmega324PB contains 1K bytes of data EEPROM memory. It is organized as a separate dataspace, in which single bytes can be read and written. The EEPROM has an endurance of at least100,000 write/erase cycles. The access between the EEPROM and the CPU is described in the following,specifying the EEPROM Address registers, the EEPROM Data register, and the EEPROM Controlregister.

See the related links for a detailed description on EEPROM Programming in SPI or Parallel Programmingmode.

Related LinksMEMPROG- Memory Programming

9.4.1 EEPROM Read/Write AccessThe EEPROM Access Registers are accessible in the I/O space.

The write access time for the EEPROM is given in Table 9-2. A self-timing function, however, lets the usersoftware detect when the next byte can be written. If the user code contains instructions that write theEEPROM, some precautions must be taken. In heavily filtered power supplies, VCC is likely to rise or fallslowly on power-up/down. This causes the device for some period of time to run at a voltage lower thanspecified as minimum for the clock frequency used. Please refer to Preventing EEPROM Corruption fordetails on how to avoid problems in these situations.

In order to prevent unintentional EEPROM writes, a specific write procedure must be followed. Refer tothe description of the EEPROM Control Register for details on this.

When the EEPROM is read, the CPU is halted for four clock cycles before the next instruction isexecuted. When the EEPROM is written, the CPU is halted for two clock cycles before the next instructionis executed.

ATmega324PB


9.4.2 Preventing EEPROM CorruptionDuring periods of low VCC, the EEPROM data can be corrupted because the supply voltage is too low forthe CPU and the EEPROM to operate properly. These issues are the same as for board level systemsusing EEPROM, and the same design solutions should be applied.

An EEPROM data corruption can be caused by two situations when the voltage is too low. First, a regularwrite sequence to the EEPROM requires a minimum voltage to operate correctly. Secondly, the CPU itselfcan execute instructions incorrectly, if the supply voltage is too low.

EEPROM data corruption can easily be avoided by following this design recommendation:

Keep the AVR RESET active (low) during periods of insufficient power supply voltage. This can be doneby enabling the internal Brown-out Detector (BOD). If the detection level of the internal BOD does notmatch the needed detection level, an external low VCC reset Protection circuit can be used. If a resetoccurs while a write operation is in progress, the write operation will be completed provided that thepower supply voltage is sufficient.

9.5 I/O MemoryThe I/O space definition of the device is shown in the Register Summary.

All device I/Os and peripherals are placed in the I/O space. All I/O locations may be accessed by theLD/LDS/LDD and ST/STS/STD instructions, transferring data between the 32 general purpose workingregisters and the I/O space. I/O Registers within the address range 0x00-0x1F are directly bit-accessibleusing the SBI and CBI instructions. In these registers, the value of single bits can be checked by usingthe SBIS and SBIC instructions.

When using the I/O specific commands IN and OUT, the I/O addresses 0x00-0x3F must be used. Whenaddressing I/O Registers as data space using LD and ST instructions, 0x20 must be added to theseaddresses. The device is a complex microcontroller with more peripheral units than can be supportedwithin the 64 location reserved in Opcode for the IN and OUT instructions. For the Extended I/O spacefrom 0x60..0xFF in SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used.

For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/Omemory addresses should never be written.

Some of the Status Flags are cleared by writing a '1' to them; this is described in the flag descriptions.Note that, unlike most other AVRs, the CBI and SBI instructions will only operate on the specified bit, andcan therefore be used on registers containing such Status Flags. The CBI and SBI instructions work withregisters 0x00-0x1F only.

The I/O and Peripherals Control Registers are explained in later sections.

Related LinksMEMPROG- Memory ProgrammingInstruction Set Summary

9.5.1 General Purpose I/O RegistersThe device contains three General Purpose I/O Registers, General Purpose I/O Register 0/1/2 (GPIOR0/1/2). These registers can be used for storing any information, and they are particularly useful for storingglobal variables and Status Flags. General Purpose I/O Registers within the address range 0x00 - 0x1Fare directly bit-accessible using the SBI, CBI, SBIS, and SBIC instructions.

ATmega324PB


9.6 Register Description

9.6.1 Accessing 16-bit RegistersThe AVR data bus is 8 bits wide, and so accessing 16-bit registers requires atomic operations. Theseregisters must be byte-accessed using two read or write operations. 16-bit registers are connected to the8-bit bus and a temporary register using a 16-bit bus.

For a write operation, the low byte of the 16-bit register must be written before the high byte. The low byteis then written into the temporary register. When the high byte of the 16-bit register is written, thetemporary register is copied into the low byte of the 16-bit register in the same clock cycle.

For a read operation, the low byte of the 16-bit register must be read before the high byte. When the lowbyte register is read by the CPU, the high byte of the 16-bit register is copied into the temporary registerin the same clock cycle as the low byte is read. When the high byte is read, it is then read from thetemporary register.

This ensures that the low and high bytes of 16-bit registers are always accessed simultaneously whenreading or writing the register.

Interrupts can corrupt the timed sequence if an interrupt is triggered and accesses the same 16-bitregister during an atomic 16-bit read/write operation. To prevent this, interrupts can be disabled whenwriting or reading 16-bit registers.

The temporary registers can also be read and written directly from user software.

9.6.2 EEPROM Address Register Low and High Byte

The EEARL and EEARH register pair represents the 16-bit value, EEAR. The low byte [7:0] (suffix L) isaccessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01. Formore details on reading and writing 16-bit registers, refer to Accessing 16-bit Registers.


Name: EEARL and EEARHOffset: 0x41 [ID-000004d0]Reset: 0xXXProperty:

When addressing as I/O Register: address offset is 0x21

ATmega324PB


Bit 15 14 13 12 11 10 9 8 EEAR[11:8]

Access R/W R/W R/W R/W Reset x x x x

Bit 7 6 5 4 3 2 1 0 EEAR[7:0]

Access R/W R/W R/W R/W R/W R/W R/W R/W Reset x x x x x x x x

Bits 11:0 EEAR[11:0]:EEPROM AddressThe EEPROM Address Registers EEARH and EEARL specify the EEPROM address in the 1K BytesEEPROM space. The EEPROM data bytes are addressed linearly between 0 and 1023. The initial valueof EEAR is undefined. A proper value must be written before the EEPROM may be accessed.

9.6.3 EEPROM Data Register


Name: EEDROffset: 0x40 [ID-000004d0]Reset: 0x00Property:

When addressing as I/O Register: address offset is 0x20

Bit 7 6 5 4 3 2 1 0 EEDR[7:0]

Access R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0

Bits 7:0 EEDR[7:0]:EEPROM DataFor the EEPROM write operation, the EEDR Register contains the data to be written to the EEPROM inthe address given by the EEAR Register. For the EEPROM read operation, the EEDR contains the dataread out from the EEPROM at the address given by EEAR.

9.6.4 EEPROM Control Register

Name: EECROffset: 0x3F [ID-000004d0]Reset: 0x00Property:

When addressing as I/O Register: address offset is 0x1F

ATmega324PB


Bit 7 6 5 4 3 2 1 0 EEPM[1:0] EERIE EEMPE EEPE EERE

Access R/W R/W R/W R/W R/W R/W Reset x x 0 0 x 0

Bits 5:4 EEPM[1:0]:EEPROM Programming Mode BitsThe EEPROM Programming mode bit setting defines which programming action that will be triggeredwhen writing EEPE. It is possible to program data in one atomic operation (erase the old value andprogram the new value) or to split the Erase and Write operations into two different operations. TheProgramming times for the different modes are shown in the table below. While EEPE is set, any write toEEPMn will be ignored. During reset, the EEPMn bits will be reset to 0b00 unless the EEPROM is busyprogramming.

Table 9-1.EEPROM Mode Bits

EEPM[1:0] Programming Time Operation

00 3.4ms Erase and Write in one operation (Atomic Operation)

01 1.8ms Erase Only

10 1.8ms Write Only

11 - Reserved for future use

Bit 3 EERIE:EEPROM Ready Interrupt EnableWriting EERIE to one enables the EEPROM Ready Interrupt if the I bit in SREG is set. Writing EERIE tozero disables the interrupt. The EEPROM Ready interrupt generates a constant interrupt when EEPE iscleared. The interrupt will not be generated during EEPROM write or SPM.

Bit 2 EEMPE:EEPROM Master Write EnableThe EEMPE bit determines whether writing EEPE to '1' causes the EEPROM to be written.When EEMPE is '1', setting EEPE within four clock cycles will write data to the EEPROM at the selectedaddress.

If EEMPE is zero, setting EEPE will have no effect. When EEMPE has been written to '1' by software,hardware clears the bit to zero after four clock cycles. See the description of the EEPE bit for anEEPROM write procedure.

Bit 1 EEPE:EEPROM Write EnableThe EEPROM Write Enable Signal EEPE is the write strobe to the EEPROM. When address and data arecorrectly set up, the EEPE bit must be written to '1' to write the value into the EEPROM. The EEMPE bitmust be written to '1' before EEPE is writ

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