I need to program a ATMega328P on a breadboard, running on an external crystal at 8 MHz.
All of the guides I can find either use the arduino environment and describe a 16 MHz config, or using the 8 MHz internal oscillator - which is too inaccurate for this project.
How do I do this? Configure the chip to run at 8 MHz and upload the program?
myself as of 3 hours ago.
- Get an arduino or similar, install the ArduinoISP sketch
- Connect the two as described here: https://www.arduino.cc/en/Tutorial/ArduinoToBreadboard
- Change the board to Arduino Pro or Pro Mini, Processor to 3.3V, 8Mhz, Programmer: Arduino as ISP
- Hit burn bootloader button
- Load up the sketch that you want on the device
- Without changing anything, use "Upload using programmer"
- Remove arduino, fix wiring changes required to use as programmer
Committed to Electronics Stackexchange for posterity. Or so I can find it when I forget next time...