How to use the GPIO version of avrdude on the Raspberry Pi

Introduction

I previously showed an implementation of a AVR ISP programmer using the Raspberry Pi GPIO port which can be used to program Atmel's AVR range of microcontrollers with avrdude. An ISP programmer based on this design was incorporated into a shield to interface to the RFM12B radio module. This post explains how to use avrdude to actually program devices.

Software installation

Download the patched version of avrdude from http://project-downloads.drogon.net/files/. I also keep a copy in the RPi_RFM12B_ISP respository, https://github.com/stevemarple/RPi_RFM12B_ISP/tree/master/software/avrdude. You will probably want the armhf (hardware floating-point) version. Download the documentation package for avrdude too. Install the packages using "dpkg -i". For example

sudo dpkg -i avrdude_5.10-4_armhf.deb
sudo dpkg -i avrdude-doc_5.10-4_all.deb

Using avrdude over the GPIO interface is problematic for users other than root. The easiest solution is to give the avrdude binary setgroup permission:

sudo chmod g+s /usr/bin/avrdude

Usage

Selecting the GPIO programmer is simply a matter of including "-P gpio -c gpio" options; the -P option specifies that the GPIO port is used (as opposed to USB, serial or parallel interfaces) whilst the -c option selects the correct programmer type on that port.

For example, to check the signature on an ATmega328P execute the command

avrdude -P gpio -c gpio -p atmega328p

To read the fuses execute the command

avrdude -P gpio -c gpio -p atmega328 -U lfuse:r:-:h -U hfuse:r:-:h -U efuse:r:-:h

Customisation

The packages above define a single programmer called gpio which uses the gpio interface on GPIO pins 8 to 11. Since the RFM12B shield for Raspberry Pi implements two independent programmers I prefer to use gpio0 and gpio1. You can add these by creating a .avrduderc file in your home directory. The file should contain:

programmer
  id    = "gpio0";
  desc  = "Use sysfs interface to bitbang GPIO lines";
  type  = gpio;
  reset = 8;
  sck   = 11;
  mosi  = 10;
  miso  = 9;
;

programmer
  id    = "gpio1";
  desc  = "Use sysfs interface to bitbang GPIO lines";
  type  = gpio;
  reset = 7;
  sck   = 11;
  mosi  = 10;
  miso  = 9;
;