ECE 447 Fall 2009

Lecture 3: TI MSP430 Introduction

ECE447: General Microcontroller Characteristics

• Integration of a CPU plus multiple peripherals on a single chip.

• Low cost for high volume applications.• Lower clock frequencies when compared to

devices like microprocessors and DSPs.– Typical range for microcontrollers: up to 100Mhz.

• Low power consumption, allowing battery operation.

• Data/Instruction word sizes from 4-bit to 32-bit• Limited memory, typically less than 1 Mbyte.• Various I/O pin-out configurations, from low to

high (8 to 150 pins).

ECE 447: Basic Computer System

CPUMemoryProgram + Data

I/O Interface

ParallelI/O Device

SerialI/O Device

Data Bus

Address Bus

Control Bus

Parallel Data

Serial Data

ECE 447: Microprocessor vs. Microcomputer

Microprocessor – A processor unit typically with only basic I/O interface, off-chip memory.

e.g.: Intel 8008, 8086, 80486, Pentium, Pentium 4, Core2Duo, PowerPC

Single-chip Microcomputer – A processor unit with on-chip memory, I/O devices, and often other peripheral devices such as timers and A to D.

e.g.: Intel 8048, Motorola 68HC11/12, TI MSP430

ECE 447: Microprocessor vs. Microcomputer

Microprocessor – A processor unit typically with only basic I/O interface, off-chip memory.

e.g.: Intel 8008, 8086, 80486, Pentium, Pentium 4, Core2Duo, PowerPC

Single-chip Microcomputer – A processor unit with on-chip memory, I/O devices, and often other peripheral devices such as timers and A to D.

e.g.: Intel 8048, Motorola 68HC11/12, TI MSP430

ECE 447: Processor Evolution

Early microcroprocessors

performance integration

General-purposemicroprocessors

Single-chip microcomputers

- small price- low power consumption- built-in memory- built-in I/O devices

- high speed- long word size

x 1 x 10

(e.g., Pentium, Athlon, Power PC) (e.g., MC68HC11, MSP430)

(8080, 6800, Z80)

volumesold

ECE 447: Microcontroller Applications

• Cars– Engine fuel injection– Transmission control– Suspension and ride control– Instrument display– Braking system

• Home Appliances– Washing machine– Microwave oven– Refrigerator

• Sports Equipment– Exercise Machine– Heart Rate Monitor

ECE 447: Microcontroller Applications

• Consumer Electronics– Digital/Film cameras– Remote Controls– Televisions– CD players– Telephone

• Computer Peripherals– Printers– Scanners– Disk drive controllers

• Robots– The Brains

ECE 447: Architecture vs. Organization vs. Realization

Architecture: The instruction set and input/output capabilities available to the programmer

Organization: The implementation of the architecture in block diagram form

Realization: Actual implementation of an organization in a given technology, eg: CMOS

High

Level of Abstraction

LOW

ECE 447: Acronyms Used

• CPU - Central Processing Unit := ALU (Arithmetic Logic Unit) + Control

• RAM - Random Access Memory := Read/Write Memory

• ROM - Read Only Memory (non-volatile)

• EPROM – Erasable Programmable ROM

• EEPROM - Electrically Erasable Programmable ROM

• SPI - Serial Peripheral Interface (synchronous serial communication interface)

• ADC - analog-to-digital converter

• DAC – digital-to-analog converter

• Port –Parallel I/O providing digital data lines (A,B,C,D,E)

ECE447: MSP430 Microcontroller Characteristics

• 16 bit RISC CPU:– Compact core design reduces power consumption

and cost– 16-bit data bus– 27 core instructions and 7 addressing modes– Extensive vectored-interrupt capability

• On-chip features:– Programmable flash memory and SRAM– 10/12/16-bit ADC, 12-bit dual DAC– Timer capture and comparator systems– Operational Amplifiers– Watchdog and Supply Voltage Supervisor– Communication systems (I2C, SPI)

ECE 447: MSP430 Block Diagram

ECE447: MSP430 Microcontroller Characteristics

• Low Power Consumption:– 0.1 A for RAM data retention– 0.8 A for real-time clock mode operation– 250 A/MIPS during active operation– Less than 50 nA port leakage current

• Low Voltage Operation– Vcc from 1.8V to 3.6V

• Flexibility and Performance– Startup less than 1 sec– Instruction processing on bits, bytes, or words– Up to 256 kBytes of Flash, up to 25 Mhz Clock– Pin-outs from 14 pins up to 100 pins– Embedded Debug/Emulation capability (JTAG)– Wide Range of Peripherals

ECE447: MSP430 Outside ViewPin-Out (F2013)

• Most pins have multiple features (pin multiplexing)• Pin limitations should be taken into account when

designing a system so that pin conflicts are avoided• Larger devices allow more simultaneous I/O functions• Some functions are available on many pins (ie: TA0,

TA1)• First task of a program is to configure the functions of

each pin

ECE447: MSP430 Inside ViewFunctional Block Diagram (F2013)

ECE447: MSP430 Inside ViewFunctional Block Diagram (F2013)

• This portion shows the CPU and its supporting hardware.

• Basic Clock Subsystem• Emulation, JTAG, and Spy-Bi-Wire are

used for communication with a host computer for downloading a program and debugging.

ECE447: MSP430 Central Processing Unit

• The MSP430 is a RISC (Reduced Instructions Set Computing) architecture:– Instructions set includes:

• 27 physical instructions;• 24 emulated instructions.

– Designed with static logic, which allows the CPU to be stopped and retain its state until it is restarted.

– Arithmetic Logic Unit which performs computation.– Interconnect by a using a common memory address

bus (MAB) and memory data bus (MDB) - Von Neumann architecture.

– A set of 16 registers designated R0 - R15.

ECE447: MSP430 Central Processing Unit Register Map

A set of 16 registers designated R0 - R15.PC: Program Counter contains the address

of the next instruction to be executed.SP: Stack Pointer to the address of the stack

frame. The stack is primarily responsible for storing the return address of subroutine calls.

SR: Status Register contains a set of flags – The C,Z,N, and V flags provide information from

the last arithmetic operation.– The GIE flag enables the maskable interrupts.– The CPUOFF, OSCOFF, SCG0 and SCG1

flags control the operation of the MCU. Use of these flags allow operation in low power modes.

CG1/CG2: Constant Generator provides the six most frequently used values so that they do not need to be fetched from memory.

ECE447: MSP430 Inside ViewFunctional Block Diagram (F2013)

• The main blocks are linked by the memory address bus (MAB) and the memory data bus (MDB)

• The device has 2kB of flash (1Kb is in the F2003)

• The device has 128 bytes of RAM• The brownout protection comes into

action when the supply voltage drop below an operational level.

ECE447: MSP430 Memory

• All memory is byte addressable (8-bits) and a byte is the smallest entity that can be transferred to and from memory.

• The MSP430 memory address bus (MAB) is 16 bit wide so there are 216=65,536= 64K = 0x10000 addresses.

• The MSP430X (like the F4618) architecture adds four bits to the address bus and CPU register to allow for 220 addresses.

• The MSP430 memory data bus is 16 bits wide and can transfer either a word of 16 bits or a byte of 8 bits.– Bytes can be accessed at any address, but words must be

accessed on a word aligned address (an even address value)

• The MSP430 is a little-endian ordered machine. The low ordered byte is stored at the lower address.

ECE 447: Area for Single Bit Cell

Assumes 65 nm technology

20 0.8 1.1 1.1 1.1 1.6 3.3

humanhair

ROM EPROMFlash

EPROM FRAM EEPROM RAM

ECE447: MSP430 Memory Map

Memory Address Description Access End: 0FFFFh

Start: 0FFE0h I nterrupt Vector Table

Word/Byte

End: 0FFDFh

Flash/ ROM

0F800h Start * :

01100h

Word/Byte

010FFh End * : 0107Fh I nformation Memory

Start: 01000h (Flash devices only) Word/Byte

End: 0FFFh Start: 0C00h

Boot Memory (Flash devices only)

Word/Byte

09FFh End * : 027Fh RAM

Start: 0200h Word/Byte

End: 01FFh Start: 0100h

16-bit Peripheral modules Word

End: 00FFh Start: 0010h

8-bit Peripheral modules Byte

End: 000Fh Start: 0000h

Special Function Registers Byte

• All memory including RAM, Flash, information memory, Special Function Registers (SFRs), and peripheral registers.

• Starred (*) start and end addresses vary based on the particular MSP430 variant

ECE447: MSP430 Inside ViewFunctional Block Diagram (F2013)

• Six Peripheral function blocks are shown. Many more exist in larger devices such as the F4618– 16 bit Sigma Delta ADC– Port P1 8 bit I/O– Port P2 2 bit I/O– Watchdog timer– Timer_A2 (2 Compare/Capture

Registers)– Universal Serial Interface

ECE 447: I/O Device Architecture

…..

Control registersinstructions

…..

Status registersstatus of the device

Data registers

…..

I/O device

address1/name1

addressN/nameN

. . . . .

inputs (operands)

outputs (results)

ECE 447: Input/Output Register Types

1. Control registers - hold instructions that regulate the operation of internal I/O devices

2. Status registers - indicate the current status of internal I/O devices

3. Data registers - hold the input data sent to the I/O device and output data generated by this device

4. Data direction registers - control the direction (in or out) of the data flow to/from bidirectional data registers

ECE 447: I/O Addressing Schemes

Memory mapped I/O

(e.g., Motorola, TI)

0

MAX

I/O

Control lines: read/write

Separate I/O

(e.g., Intel)

0

MAX

I/O0

max

Control lines: read/write memory/io

(Same Instructions) (Different Instructions)

ECE447: MSP430 Memory-Mapped Input and Output

• Digital Input and Output are arranged on a set of pins and grouped in ports.

• The MSP430 designates ports by number (P1, P2,…)

• Pins can be configured as inputs or outputs

• Internally, I/O ports appear as memory register (peripheral register)– Each port is associated with a byte.– Each bit in the byte corresponds to a specific I/O pin.– Each register can be read, written, and modified.

ECE447: MSP430 Memory-Mapped Input and Output

• Each port has several registers that are used to read, write, and configure it.

• Port P1 has 8 registers, three are the most important:– Port P1 input, P1IN: Reading this returns the logical

values on the P1 pins if they are configure for digital input and output.

– Port P1 output, P1OUT: Writing to this register sends the value to be driven onto the port output pins if it is configured as a digital output.

– Port P1 direction, P1DIR: A bit of 0 configures the corresponding pin as an input, which is the power-on default. Writing a 1 switches the pin to an output.

ECE447: MSP430 Additional Resources

• Resources for students working with the MSP430– MSP430 device Data Sheet

• The data sheet contains a wealth of information including device specific information.

– MPS430 Family Users Guide• Provides a detailed description of all the functional modules

within the family.• Register descriptions with bit details and reset values.

– FET User’s Guide (Flash Emulation Tool)• A good FAQ on hardware, software development, and

debugging.– Application Notes

• TI has published over 100 ANs for the MSP430, from very general topics to very specific.

– Code Examples• TI also has many code examples for the MPS430 available.