ADB Protocol ============ Resources --------- ADB - The Untold Story: Space Aliens Ate My Mouse http://developer.apple.com/legacy/mac/library/#technotes/hw/hw_01.html Apple IIgs Hardware Reference Second Edition [p80(Chapter6 p121)] ftp://ftp.apple.asimov.net/pub/apple_II/documentation/Apple%20IIgs%20Hardware%20Reference.pdf ADB Keycode http://72.0.193.250/Documentation/macppc/adbkeycodes/ http://m0115.web.fc2.com/m0115.jpg [Inside Macintosh volume V, pages 191-192] ADB Signaling http://kbdbabel.sourceforge.net/doc/kbd_signaling_pcxt_ps2_adb.pdf ADB Overview & History http://en.wikipedia.org/wiki/Apple_Desktop_Bus Microchip Application Note: ADB device(with code for PIC16C) http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en011062 AVR ATtiny2131 ADB to PS/2 converter(Japanese) http://hp.vector.co.jp/authors/VA000177/html/KeyBoardA5DEA5CBA5A2II.html Pinouts ------- Female socket from the front 4o o3 2o o1 == 1: Data 2: Power SW(low when press Power key) 3: Vcc(5V) 4: GND Commands -------- ADB command is 1byte and consists of 4bit-address, 2bit-command type and 2bit-register. The commands are always sent by Host. Command format: 7 6 5 4 3 2 1 0 | | | |------------ address | |-------- command type | |---- register bits commands ------------------------------------------------------ - - - - 0 0 0 0 Send Request(reset all devices) A A A A 0 0 0 1 Flush(reset a device) - - - - 0 0 1 0 Reserved - - - - 0 0 1 1 Reserved - - - - 0 1 - - Reserved A A A A 1 0 R R Listen(write to a device) A A A A 1 1 R R Talk(read from a device) The command to read keycodes from keyboard is 0x2C which consist of keyboard address 2 and Talk against register 0. Address: 2: keyboard 3: mice Registers: 0: application(keyobard uses this to store its data.) 1: application 2: application(keyboard uses this for LEDs and state of modifiers) 3: status and command Communication ------------- This is a minimum information for keyboard communication. See "Resources" for detail. Signaling: ~~~~____________~~||||||||||||__~~~~~_~~|||||||||||||||__~~~~ |800us | |7 Command 0| | | |15-64 Data 0|Stopbit(0) +Attention | | | +Startbit(1) +Startbit(1) | +Tlt(140-260us) +stopbit(0) Bit cells: bit0: ______~~~ 65 :35us bit1: ___~~~~~~ 35 :65us bit0 low time: 60-70% of bit cell(42-91us) bit1 low time: 30-40% of bit cell(21-52us) bit cell time: 70-130us [from Apple IIgs Hardware Reference Second Edition] Criterion for bit0/1: After 55us if line is low/high then bit is 0/1. Attention & start bit: Host asserts low in 560-1040us then places start bit(1). Tlt(Stop to Start): Bus stays high in 140-260us then device places start bit(1). Global reset: Host asserts low in 2.8-5.2ms. All devices are forced to reset. Send request from device(Srq): Device can request to send at commad(Global only?) stop bit. keep low for 300us to request. Keyboard Data(Register0) This 16bit data can contains two keycodes and two released flags. First keycode is palced in upper byte. When one keyocode is sent, lower byte is 0xFF. Release flag is 1 when key is released. 1514 . . . . . 8 7 6 . . . . . 0 | | | | | | | | | +-+-+-+-+-+-+- Keycode2 | | | | | | | | +--------------- Released2(1 when the key is released) | +-+-+-+-+-+-+----------------- Keycode1 +------------------------------- Released1(1 when the key is released) Keycodes: Scancode consists of 7bit keycode and 1bit release flag. Device can send two keycodes at once. If just one keycode is sent keycode1 contains it and keyocode2 is 0xFF. Power switch: You can read the state from PSW line(active low) however the switch has a special scancode 0x7F7F, so you can also read from Data line. It uses 0xFFFF for release scancode. Keyboard LEDs & state of keys(Register2) This register hold current state of three LEDs and nine keys. The state of LEDs can be changed by sending Listen command. 1514 . . . . . . 7 6 5 . 3 2 1 0 | | | | | | | | | | | | | | | +- LED1(NumLock) | | | | | | | | | | | | | | +--- LED2(CapsLock) | | | | | | | | | | | | | +----- LED3(ScrollLock) | | | | | | | | | | +-+-+------- Reserved | | | | | | | | | +------------- ScrollLock | | | | | | | | +--------------- NumLock | | | | | | | +----------------- Apple/Command | | | | | | +------------------- Option | | | | | +--------------------- Shift | | | | +----------------------- Control | | | +------------------------- Reset/Power | | +--------------------------- CapsLock | +----------------------------- Delete +------------------------------- Reserved END_OF_ADB