Programming the ATtiny85 From Raspberry Pi





Introduction: Programming the ATtiny85 From Raspberry Pi

These instructions tell you how to setup and program the ATtiny85 microcontroller from a Raspberry Pi via the SPI interface. Lots of people use the Ardiuno to do this (then you can use the Arduino IDE and simplified C commands), or you can use a USB based programmer. I do not have an Ardiuno and don't want to buy a dedicated programmer. I do have a Pi, so I was pleased to learn I could use it as a way to get into microcontroller programming.

You will need:
Raspiberry Pi
ATtiny85 chip
5 x 1K resistors (or similar)
LED of your choice
A connection to the GPIO of the Pi, and a breadboard and wire.

Based on

Step 1: Setup the Raspberry Pi

At the terminal of the Pi:

Download and build avrdude

sudo apt-get install bison automake autoconf flex git gcc
sudo apt-get install gcc-avr binutils-avr avr-libc
git clone
cd avrdude/avrdude
./bootstrap && ./configure && sudo make install

Setup SPI on the GPIO

sudo raspi-config
and Enable SPI device in the Advanced Options (see picture)
You can check this at the command line with lsmod, no need to reboot. (Maybe need to sudo modprobe spidev)

Download and build WiringPi for the gpio commands

cd ~
git clone git://
cd wiringPi

Step 2: Electrical Connections

Connect up the ATtiny85 to the Raspberry Pi GPIO (wire colours from the picture are given for reference):

GPIO pin ATtiny pin Comment
15            1                GPIO22 to Reset (through 1K, Blue wire)
17            8                3.3 V (Green wire)
19            5                MOSI (through 1K, Yellow wire)
21            6                MISO (through 1K, Orange wire)
23            7                SCLK (through 1K, Red wire)
25            4               GND (Brown wire)

(I could not find a way to do a nice table in instructables)

Step 3: Test Avrdude Connection

Test avrdude connection to the ATtiny85, we are set up with GPIO pin 22 on the ATtiny reset. We must pull this pin low to program the chip. This can be done in other ways, e.g. a switch, but I an using another pin of the GPIO to do this.

sudo gpio -g mode 22 out
sudo gpio -g write 22 0
sudo avrdude -p t85 -P /dev/spidev0.0 -c linuxspi -b 10000
sudo gpio -g write 22 1

This must give success type messages!

Step 4: Program the ATtiny85

Program the ATtiny85:

cd ~
mkdir ATtiny85
cd ATtiny85
mkdir blinky
cd blinky

create the blinky.c file and add the following code
nano blinky.c
#define F_CPU 1000000L
#include <avr/io.h>
#include <util/delay.h>

int main(void)
DDRB = 0xFF; // PORTB is output, all pins
PORTB = 0x00; // Make pins low to start

for (;;) {
PORTB ^= 0xFF; // invert all the pins
_delay_ms(100); // wait some time
return 0;

add this code to a Makefile file
nano Makefile
CFLAGS=-g -Os -Wall -mcall-prologues -mmcu=$(MCU)
all :
$(CC) $(CFLAGS) $(TARGET).c -o $(TARGET)
$(OBJ2HEX) -R .eeprom -O ihex $(TARGET) $(TARGET).hex
rm -f $(TARGET)

install : all
sudo gpio -g mode 22 out
sudo gpio -g write 22 0
sudo $(AVRDUDE) -p $(AVRDUDEMCU) -P /dev/spidev0.0 -c linuxspi -b 10000 -U flash:w:$(TARGET).hex
sudo gpio -g write 22 1
noreset : all
sudo $(AVRDUDE) -p $(AVRDUDEMCU) -P /dev/spidev0.0 -c linuxspi -b 10000 -U flash:w:$(TARGET).hex

fuse :
sudo gpio -g mode 22 out
sudo gpio -g write 22 0
sudo $(AVRDUDE) -p $(AVRDUDEMCU) -P /dev/spidev0.0 -c linuxspi -b 10000 -U lfuse:w:0x62:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m
sudo gpio -g write 22 1

clean :
rm -f *.hex *.obj *.o
(Sorry, the instructables text editor has destroyed all the tabs and spacing in the code above, the Makefile will not work without tabs in the correct place)

To compile type:
To compile and upload code to the ATtiny:
make install
To optionally send fuses:
make fuse

This program oscillates ALL 5 pins as outputs so the LED should flash.
We are programming the ATtiny directly using avr-libc.
To change the setup of the ATtiny get fuses from :

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I am lost when it comes to coding... Where should the TABS go? Can someone please post a picture of the correct code?

Thankyou so much! I had purchased 10x ATtiny84a's and had no idea, until I stumbled upon this. Much Appreciated:)

Hi, this helped me to get going, but you should update/change one thing.

After reading this post:
I noticed that the 'linuxspi' programmer by default uses the GPIO pin 25 for reset, so your reset wrapper script is not needed. Else, great work ;)

This is a fantastic tutorial, and it really helped me get started. I'd like to point out a couple things I learned along the way, however. I don't know about at the time you were doing this project, but the "linuxgpio" configuration for avrdude exists in /etc/avrdude.conf on the RPi (after you install avrdude, of course); you simply uncomment the lines and set the pins to what they should be. Second, because the AVR and the RPi both run at 3.3v, I didn't find any need to use resistors for anything other than the LED itself, and that was only to protect the LED. And finally, if you hook the LED's positive pole to one of the SPI pins, the LED will happily blink for you as the RPi uploads data, which is cool and gives some nice feedback!

Oh, and I used this with an ATmega88; I'm sure you can use it with any ATmega that supports 3.3v operation, which, for all I know, is all of them.

Works with atmega8. When I poweroff the Raspberry Pi the Reset pin GPIO 22 gets to zero, stopping the program on the microcontroller. I added a pullup resistor of 10 k to 3.3 v to GPIO22 and now it works after Pi poweroff too :) . Thank you. I made it but I don't yet have a camera / photo capable phone so no images...

Is it possible to program Atmega8-8PU using this?