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Custom Boot Message f005-MK312-BT
Custom Boot Message f005-MK312-BT
 
 
README.md
README.md
 
 

README.md

MK312-BT Firmware

  1. We are using an external 8mhz crystal instead of the internal RC oscillator that the original uses. We need to set the fuses to enable this.
    • LOW FUSE: 0xFF
    • HIGH FUSE: 0xDC
  2. A patched version of buttshock-et312-frankenbutt-f005 is recommended.
  3. The firmware needs to be changed to replace the up/down arrows on the UI with left right arrows (this is because the LCD we use has a different character set)
  4. Obtain or modify a copy of the firmware and flash the result onto the AVR.
  5. If you don't want to use an external crystal - we need to set the calibration byte for the internal oscillator. If programming a blank chip you first need to read the calibration bytes of that part (i.e. using avrdude -t “dump calibration” the fourth byte is the calibration byte for 8MHz or use atmel studio to read the oscillator calibration byte). Then program that byte into 0x3fff in your firmware. These bytes will differ on different chips even from the same batch. The firmware reads that byte to set OSCCAL on startup. If the byte is inaccurate various problems and failures will occur related to timing, interrupts, and serial communication. Just use an external crystal dammit.