Transcript Presentazione di PowerPoint

©F.M. Rietti
Embedded Systems I
Controllers Data Sheets
©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
2
©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
3
©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 boards
(IT law DPR328/2001 designing is for B
engineers, we study as C)
LM-18 Computer Science SSI
Embedded Systems I
4
©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
5
©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
6
©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
doesn’t work!
LM-18 Computer Science SSI
Embedded Systems I
7
©F.M. Rietti
Data Sheets Hi Lights (cont)
• Power Dissipation
– Based on package heat transfer limitations
not device power consumption
• 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
8
©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
9
©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
10
©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
11
©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
12
©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
LM-18 Computer Science SSI
Embedded Systems I
13