Sun Keyboard Protocol
Prebuilt converter is available here: https://geekhack.org/index.php?topic=72052.0
https://github.com/tmk/tmk_keyboard/tree/master/converter/sun_usb
https://geekhack.org/index.php?topic=105671.0
Modern Type 4 and 5 keyboards uses 8Pin mini DIN.
___ ___
/ |_| \
/ 8 7 6 \
| 5 4 3 |
\_ 2 1 _/
\_____/
(receptacle)
Wiring:
Pin mini DIN MCU
----------------------------------
1 GND GND
2 GND GND
3 5V
4 RX/TX(Mouse)
5 RX PD3
6 TX PD2
7 GND GND
8 5V VCC
Signal: Asynchronous, Negative logic, 1200baud, No Flow control
Frame format: 1-Start bit, 8-Data bits, No-Parity, 1-Stop bit
AVR USART engine expects positive logic while Sun keyboard signal is negative. To use AVR UART engine you need external inverter in front of RX and TX pin. Otherwise you can use software serial to communicate the keyboard.
This firmware uses software serial by default, so you don't need any inverter. It can be still built with 'make HARDWARE_SERIAL=y' to enable hardware serial if you have inverter. You can use 74LS04 for example.
0x01 Reset
Keyboard responds with following byte sequence:
Success: 0xFF 0x04 0x7F
Fail: 0x7E 0x01 0x7F
0x02 Bell On
0x03 Bell Off
0x0A Click On
0x0B Click Off
0x0E LED
followed by LED status byte:
bit: 3 2 1 0
LED: CapsLk ScrLk Compose NumLk
0x0F Layout
Keyboard responds with 'Layout Response' 0xFE 0xXX
0x7F Idle
means no keys pressed.
0xFE Layout Response
0xFF Reset Response(followed by 0x04)
http://kentie.net/article/sunkbd/KBD.pdf
http://kentie.net/article/sunkbd/page2.htm
http://blog.daveastels.com.s3-website-us-west-2.amazonaws.com/2014/12/27/type-3-keyboard.html
https://codeberg.org/xelalexv/suniversal