Embedded Programming Master Class

  • By Joris Navarro
  • workshops

Embedded programming Master Class with guillem and victor

Support document

Intro

ATtiny 44 & 45

the first number “4” is the memory 4k ()

the second number is the familly

in the AVR familly

tiny familly arduino use the mega familly

why the software to compile are open source

questions about chip : octopart

ATTINY44A-SSU A-SSU is for the packaging (basicaly the shape) DIP (through hole components) is the shape you use on breadboard

throug holes component are becoming harder to find, that is why we use smd components

the chip has pins 1 for VCC 1 for Ground pins (4) have extra fonctionality on top (MISO, MOSI, RST, .. for ISP) but we can use them to other purposes

the chip does not know PIN3, arduino abstract this for us

Install boards in Arduino Follow these instructions

select Attiny24/44/84 change programmer USBTinyISP

be carefull of the pin number arduino and chip ones are differents

open blink exemple

change pin number

Send it to the board

What arduino bring

The blue blocks are from arduino

AVR GCC toolchain : avr-gcc + avr-ar + avr -objcopy + avrdude

read the datadheet to knwo how the chip works the memory is very important its a big array of switches

the first row (registers) change the state of the pins

memory switch have address from 0 to … go to register summary

a row hav 8 switches (0 yo 7), a row hav an address 0x

rows: PORTA DDRA PINA are used to control our pins

here we want to use PA7 (pin 6 on chip)

1 Bit is 0 or 1 8 bits is 1 Byte 10110101

DDRx register is used to tell if pin is an input or an output (data direction register) PORTx (port x data register) read data from pin PINx (port x input register) write data

to write into memory we need to write all row

DDR : 1 is output

Bit   7 6 5 4 3 2 1 0
DDRA   1 0 0 0 0 0 0 0

DDRA (var from avr/io.h) 0b prefiw is used to tell it’s a byte

so DDRA will be set to 0b10000000 (for 0b 1000000) to turn pin 7, actually #7 of the chip, as an output

DDR is a marco for the memory address 0x1A

same for PORTA to write on pins 0 to 7

Blink exemple in C

`#include <avr/io.h> #include <util/delay.h>

int main(void) { DDRA = 0b10000000;

while (1) {
  PORTA = 0b01000000;
  _delay_ms(1000);

  PORTA = 0b00000000;
  _delay_ms(1000);
}

}`

Bit shifting `1«1 = 0b00000001 1«2 = 0b00000010 1«3 = 0b00000100 …

1«6 = 0b01000000`

Bit masking

PORTA = 0b00000000;

OR operation:

0b01000000 <= (1<<6) 0b00000000 <= PORTA -------------------- 0b01000000 <= PORTA

PORTA = 0b01000000;

PORTA = (1 « 6) PORTA

Macros ‘#define pinOutput(port, pin) ((1 « pin) | port)

call :

pinOutput(DDRA, 6)

is equivalent as

PORTA = (1 « 6) PORTA;

how arduino works

`#include <avr/io.h> #include <util/delay.h>

int main(void) { setup();

while (1) {
  loop();
}

}`

Build chain

GCC-AVR to compile AVRDUDE to upload

ISP

Fuses : There are 3 bytes of permanent storage in the chip called fuse low byte, fuse high byte and fuse extended byte

Generator

Makefile

Tuto

Make run commands in Makefile without argument it compile

we have to run twice make make us

avr-gcc -mmcu=attiny44 -Wall -Os -DF_CPU=1000000000 -I./ -o hello.button.44.out

attiny44 1Mhz for internal clock

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