AVR Toolkit

This code supports AVR MCUs utilizing avr-libc by providing additional support libraries for the PWMs and other handy hardware features. It also has some included code and scripts for helping getting other devices setup that can be used in conjunction with lots of robotic experiments and products, such as the PS3 Dual Shock Controller.

It is worth noting that at the moment, items not related directly to the AVR are mostly targeted at Raspberry Pi use. They will work on other machines, but some of the scripts may need to be modified. I hope to change that after things solidify more.

Please note that this code is covered by the MPLv2 license, which is quite liberal in how you can use it with your own software. You may find its text at https://www.mozilla.org/en-US/MPL/2.0/. If you have questions about it, the Internet is filled with FAQs, but I chose this license mostly for the benefit of everyone involved.

Build Requirements

Generally speaking, this project has been tested under Linux. It is likely to work under Windows with some finagling, but it hasn't been a focus of this project at this time. However, we accept pull requests, and we'd love to give more people access to this set of tools.

Having said that, assuming you already have your favorite flavor of Linux installed, you will need these tools:

1. cmake
2. gcc-avr
3. libc-avr
4. avrdude

Usage

There are two basic modes for building applications. The first lets you build programs for the AVR, and the second lets you build applications for the PC.

./configure -b <build_dir> avr -mcu <mcu_type> -fcpu <hz>
OR
./configure -b <build_dir> default

cd <build_dir>
make

The command for installing programs is specific to each target architecture and will be outlined using examples.

Example AVR Code:

# Prepare a build directory for the ATmega88 with a CPU speed of 8 MHz.
./configure -b build_avr avr -mcu atmega88 -fcpu 8000000
cd build_avr

# Currently, the cmake files assume you're using linuxgpio (e.g. on the
# Raspberry Pi) and have set everything up properly in /etc/avrdude.conf.
# See "Raspberry Pi Setup" for some tips on how to configure avrdude
# and properly connect your AVR directly to a Raspberry Pi.
#
# Then, to install the PWM code, for example:
make install_pwm

Example PC Code:

./configure -b build_pc default
cd build_pc

# Then, to build all control modules:
make

Raspberry Pi Setup

So, you're using a Raspberry Pi (RPi) to communicate with and program your AVR chips, are you? Well, congratulations! It's a fine little setup, and this section of the notes is specifically to guide you through that setup process. This document, however, will only talk about the SPI setup and will not cover any specifics on how to power your AVR (hint: the RPi has power and ground pins, and you should connect ALL the AVR ground pins up to a common ground, btw). While going through this section, you should refer to http://pi.gadgetoid.com/pinout.

I apologize in advance for not providing any images or diagrams just yet. I just want to get this information out to you in any form possible, even in a raw form, so that you might be able to get started.

Firstly, we're going to assume you want to use the GPIO header to program your AVR. You are free to use whatever power source you want, but you have to make sure your AVR only sends 3.3v signals back to the RPi. So, if you power the AVR using something other than the 3.3v (e.g. using the 3.3v power supply pin on the RPi), please buy a voltage level translator or build something yourself. You do not want "the magic smoke".

Anyway, you will be using the SPI pins on your RPi, which are the MOSI, MISO, and SCK pins. You also need to use one of the digital output pins as your ~RST signal for the AVR. You should also connect the RPi's GND to your AVR, even if the AVR is connected to another power source, because it will create a common ground.

I'm not exactly an EE expert, but I don't think you should encounter any ground loops (at least, I didn't, which, extrapolating from a sample size of 1, no one in the world should have probelems, haha).

Connect the SCK pins on both the RPi and AVR directly together. Then, connect the MISO on the RPi to the MOSI on the AVR. Next, quite obviously, connect the MOSI on the RPi to the MISO on the AVR. Finally, connect whatever pin you designated as the ~RST signal pin to your AVR's ~RST pin. And by the way, it wouldn't hurt to put a pull-up resistor between the AVR's ~RST pin and Vcc.

Moving on, you're ready to setup /etc/avrdude.conf on your RPi to handle data transfers with the SPI. On my model B, I chose BCM 22, allowing me physical pins {15,17,19,21,23,25}, which are located geographically close. So, assuming you use BCM 22, this is what your avrdude.conf would look like for "linuxgpio":

programmer
  id    = "linuxgpio";
  desc  = "Use the Linux sysfs interface to bitbang GPIO lines";
  type  = "linuxgpio";
  reset = 22;
  sck   = 11;
  mosi  = 10;
  miso  = 9;
;