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.

Minimal Arduino with ATmega8

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:
– 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.

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

READ  Controlling relay switches with an infrared remote

 

For more detail: Minimal Arduino with ATmega8




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