If you want to run the AVR at a higher voltage then you would need to use voltage level shifters on all the data lines because the Pi’s GPIO pins cannot tolerate more than 3.3 V. The Pi will also provide 3.3 V power and ground. 1 KΩ resistors are placed in series with each connection to limit the current. The MOSI, MISO and Serial Clock pins of the Pi and the AVR will be connected together and an additional Pi pin will control the AVR Reset. The wiring to program an AVR from the Pi is very simple. It can be clocked up to 20 MHz and it has a Universal Serial Interface or USI which is compatible with the PI’s SPI. This AVR can run at a voltage between 1.8 and 5.5 V, so it can be powered by a Pi. You can use them to measure voltage or read analog devices (a feature missing from the pi). Eight of these pins are hardware ADC which means they support analog to digital conversion.

12 pins can be used as inputs or outputs similar to the PI’s GPIO. It is a 14 pin DIP package so it’s breadboard friendly. Of course, you don’t need to buy or make a programmer if you have a Raspberry Pi, because it can do the job.įor this tutorial, I’ll be using an ATtiny24 AVR chip. I also have a DIY USB programmer that I developed. Adafruit sells a USB programmer kit that works well. The code is usually written on a PC and then compiled and uploaded to the AVR with a programmer. AVR chips run code that can be compiled from basic, C and assembly language. Often a single AVR can replace a complicated electrical circuit with multiple components. Offloading the operations to an AVR can reduce the load and is often cheaper than a dedicated LCD driver IC. Also some devices such as multi-digit LED displays can consume too much of the Pi’s CPU resources. Futhermore, there are times when there is no Pi driver available for a component such as a graphic display, but an AVR driver is available. They are a great solution for controlling projects because they are small, inexpensive, fast, can run off batteries and can interface with just about any DIY electronics including the Pi. They can often be purchased on eBay for a couple of dollars.

AVR chips such as the Atmel ATtiny or ATmega are powerful 8 bit microcontrollers.

My projects section contains many AVR based projects.

Atmel spi programmer