Unified Retro Keyboard
Welcome to the Unified Retro Keyboard Project wiki!
This wiki will collect technical notes, assembly and configuration guides, tips and more.
Downloads:
Download the latest release of the firmware here
Build notes:
Classic Keyboard build guide
Apple II notes
Encoder notes (2560-based)
Programming the Atmega chips
Make sure that the DIV8 flag is OFF (or the chip will run at 1 MHz and you will find the encoder to be very sluggish), and the ISP programming flag is enabled (if you want to be able to program via the ISP header)
The fuse settings I recommend are:
For ATMega328P
Extended: 0xFF
High: 0xD9
Low: 0xD2
This corresponds to the following fuse settings
- Brownout Detection Disabled (Extended byte)
- SPIEN (in system programming over SPI) Enabled (High byte)
- Boot flash size 2048 ((high byte)
- 8 MHz internal RC clock, 4.1 ms startup time (low byte)
All other fuses disabled.
For ATMega2560
Extended: 0xFF
High: 0x99
Low: 0xE7
This corresponds to the following fuse settings
- Brownout Detection Disabled (Extended byte)
- JTAGEN (in system programming over JTAG) Enabled (High byte)
- SPIEN (in system programming over SPI) Enabled (High byte)
- Boot flash size 4096 ((high byte)
- Full Swing Oscillator, xtal, fast rise, 4.1 ms startup (low byte)
All other fuses disabled.