Minimal Arduino with ATmega8




Like me, you may have a few old Arduino boards or ATmega8 chips (in the boards) laying around from when you were first playing with Arduino. Those chips can still be really useful as the heart of a tiny “Minimal Arduino” setup.

A normal Arduino board contains support components that make it easy to use. If you want a smaller footprint, you can get one of the many Arduino work-alike boards. But if you want a really small footprint, and reuse your old parts, you can make an Arduino board using just five components:

Minimal Arduino with ATmega8




– ATmega8 chip
– single 10k resistor
– single 0.1uF capacitor
– tiny breadboard
– some hookup wire
(On the left, an IR remote controlled BlinkM. On the right an IR remote controlled RGB LED)

The Circuit

The minimal Arduino circuit is dead simple.  It relies on the internal 8MHz oscillator (like the Lilypad Arduino).  And like the Lilypad, it doesn’t include a USB-to-serial. You have to provide that with a FTDI USB-to-serial cable or with an old Arduino board.
Eagle-format minimal-arduino.sch file

Getting the Arduino bootloader into the ATmega8

While the circuit is very similar to a Lilypad Arduino, the chip used is different. The ATmega8 has less memory and must be programmed slightly differently than the Lilypad’s ATmega168.

So a modified Arduino bootloader needs to be programmed into the ATmega8.  The bootloader is a small program on the chip that listens to the serial port on power up and can reprogram the rest of the chip if instructed to.  Here, a variant of the standard “Arduino NG” bootloader is used.  The modifications are:
– uses internal 8MHz oscillator (no external part required)
– serial speed is 38400 instead of 19200 for faster uploads

Files for Minimal Arduino ATmega8 bootloader:
atmega8_noxtal.zip
Unzip this file into the “arduino-0015/hardware/bootloaders” directory of your Arduino installation to create the directory “atmega8_noxtal”. The zip file contains:
– ATmegaBOOT.hex — the actual bootloader to program
– ATmegaBoot.c — the source code of the bootloader
– Makefile — Makefile to produce & program the bootloader

Minimal Arduino with ATmega8 schematic

Actually programming the bootloader to the ATmega8 chip can be done in a few ways. I prefer using an AVRISPmkII programmer and an old Arduino board.  Seat the ATmega8 into the Arduino, plug the AVRISP into the 6-pin “ICSP” header, plug both into USB, and program the ATmegaBOOT.hex file. If you are familiar with the command-line, go into the “atmega8_noxtal” directory and type “make isp” to program. If not, you can have the Arduino software program it for you once you tell it about this new kind of Arduino board.

For more detail: Minimal Arduino with ATmega8




This Post / Project can also be found using search terms:

  • arduino atmega8
  • arduino atmega8 projects
  • atmega 8 arduino ir project
  • usb wifi connect atmega8
Clip to Evernote

Leave a Comment

(Spamcheck Enabled)

Read previous post:
Arduino based Split Flap game
Arduino based Split-Flap game

We have a great Dutch Holiday tradition called sinterklaas (5th of december, this is what the US Santa is based...

Close
Scroll to top