Sun to USB keyboard protocol converter ====================================== Target MCU is ATMega32u4 but other USB capable AVR will also work. Supported keyboards: Sun Type 5 Keyboard, CTCSP SHORT TYPE KEYBOARD(CKUB) CTCSP SHORT TYPE KEYBOARD: http://imgur.com/a/QIv6p Connector --------- 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 Protocol -------- Singnal: 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 exteral inverter in front of RX and TX pin. Otherwise you can software serial routine to communicate the keyboard. This converter uses software method, you doesn't need any inverter part. Commands From System To Keyboard 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 Commands From Keyboard To System 0x7F Idle means no keys pressed. 0xFE Layout Response 0xFF Reset Response(followed by 0x04) Reference http://kentie.net/article/sunkbd/page2.htm http://kentie.net/article/sunkbd/KBD.pdf Build Firmware -------------- Just use 'make' $ cd sun_usb $ make Then, load the binary to MCU with your favorite programmer.