©F.M. Rietti

Embedded Systems I

Controllers Data Sheets

LM-18 Computer Science SSI Embedded Systems I

2

©F.M. Rietti

What is a Data Sheet?

• Datasheet is a document written by controller manufacturer, reporting all major characteristics.

• Reading Datasheets we are able to decide if controller is good for our scopes

• Two reading modes:– Electronic Engineer

– Systems & Software Engineer

• Both for Single Chip (MCU) or Single Board

LM-18 Computer Science SSI Embedded Systems I

3

©F.M. Rietti

Electronic Eng. Point of view

• For an Electronic Engineer datasheet is important:– To design circuits schemas around controller– To design PCB layout– To design system case

• Dirty or clean environment

• Working temperature range

LM-18 Computer Science SSI Embedded Systems I

4

©F.M. Rietti

Sys & SW Eng. Point of View

• Important data are common for board with a single MCU and some auxiliary chips and complex single board with some peripherals on board, connected from PCB tracks

• Sys & SW engineer choice a ready made board to build embedded system, adding peripherals and SW Sys & SW engineers cannot design boardsSys & SW engineers cannot design boards (IT law DPR328/2001 designing is for B engineers, we study as C)

LM-18 Computer Science SSI Embedded Systems I

5

©F.M. Rietti

Data Sheets Hi Light

• Temperature (some chips are made in various T ranges)– Standard 0 ÷ +40 (or +70) °C– Extended –40 ÷ +85 °C– Automotive –40 ÷ +110 °C– Storage

• Price increase with T range

LM-18 Computer Science SSI Embedded Systems I

6

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Packaging– No interest for Sys & SW engineers, but chips

with pins and socket can be go out for hi knocks or vibrations, superficial mounting is more robust.

LM-18 Computer Science SSI Embedded Systems I

7

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Supply Voltage (nominal ± range)– Various values from controller market, DC type– Multiple of 1.2V allow battery power supply

(Ni-Cd, Ni-Mh, Thionil chlorure, …)– Large availability of DC-DC Integrate Circuits

to adapt increasing or decreasing voltage.Remember in DC mode transformers Remember in DC mode transformers doesn’t work!doesn’t work!

LM-18 Computer Science SSI Embedded Systems I

8

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Power Dissipation– Based on package heat transfer Based on package heat transfer

limitations not device power limitations not device power consumptionconsumption

• Power Supply current– Remember: if controller has outputs,

digital or analog, must consider total sum of currents

• Max Electrical Power = Vcc * Iccmax

LM-18 Computer Science SSI Embedded Systems I

9

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Clock– Internal– External (Crystal required)– Range

• Always remember Fourier series for a square wave: sum of odd harmonics, with amplitude equal V/n.

LM-18 Computer Science SSI Embedded Systems I

10

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Data bits

• Address bits

• Memory amount– Program Space– Data Space

• Interrupts Line(s)

• Timer(s)

LM-18 Computer Science SSI Embedded Systems I

11

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Interfaces– Digital signals

• IN (Impedance & Maximum Voltage)– TTL logic

– counter

• OUT (Voltage & Maximum Current )– TTL logic

– PWM

LM-18 Computer Science SSI Embedded Systems I

12

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Interfaces (cont)– Analog signals

• IN (Impedance, Max. Voltage, current sensing or voltage sensing & resolution bits)

• OUT (Max. current, Voltage or Current & resolution bits)

– Communication (wired)• EIA RS232

• Ethernet

LM-18 Computer Science SSI Embedded Systems I

13

©F.M. Rietti

Data Sheets Hi Lights (cont)

• Interfaces (cont)– Communication (wired)

• EIA RS232

• Ethernet

• CAN, LIN, MODBUS, PROFIBUS, …

– Communication (radio)• Wi-Fi

• Bluetooth

• XBee