ADB.txt

   1 ADB Protocol
   2 ============
   3
   4 Resources
   5 ---------
   6 ADB - The Untold Story: Space Aliens Ate My Mouse
   7     http://developer.apple.com/legacy/mac/library/#technotes/hw/hw_01.html
   8 Apple IIgs Hardware Reference Second Edition [p80(Chapter6 p121)]
   9     ftp://ftp.apple.asimov.net/pub/apple_II/documentation/Apple%20IIgs%20Hardware%20Reference.pdf
  10 ADB Keycode
  11     http://72.0.193.250/Documentation/macppc/adbkeycodes/
  12     http://m0115.web.fc2.com/m0115.jpg
  13     [Inside Macintosh volume V, pages 191-192]
  14 ADB Signaling
  15     http://kbdbabel.sourceforge.net/doc/kbd_signaling_pcxt_ps2_adb.pdf
  16 ADB Overview & History
  17     http://en.wikipedia.org/wiki/Apple_Desktop_Bus
  18 Microchip Application Note: ADB device(with code for PIC16C)
  19     http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en011062
  20 AVR ATtiny2131 ADB to PS/2 converter(Japanese)
  21     http://hp.vector.co.jp/authors/VA000177/html/KeyBoardA5DEA5CBA5A2II.html
  22
  23
  24 Pinouts
  25 -------
  26     Female socket from the front
  27
  28       4o  o3
  29      2o    o1
  30         ==
  31
  32     1: Data
  33     2: Power SW(low when press Power key)
  34     3: Vcc(5V)
  35     4: GND
  36
  37
  38 Commands
  39 --------
  40     ADB command is 1byte and consists of 4bit-address, 2bit-command
  41     type and 2bit-register. The commands are always sent by Host.
  42
  43     Command format:
  44     7 6 5 4 3 2 1 0
  45     | | | |------------ address
  46             | |-------- command type
  47                 | |---- register
  48
  49     bits                commands
  50     ------------------------------------------------------
  51     - - - - 0 0 0 0     Send Request(reset all devices)
  52     A A A A 0 0 0 1     Flush(reset a device)
  53     - - - - 0 0 1 0     Reserved
  54     - - - - 0 0 1 1     Reserved
  55     - - - - 0 1 - -     Reserved
  56     A A A A 1 0 R R     Listen(write to a device)
  57     A A A A 1 1 R R     Talk(read from a device)
  58
  59     The command to read keycodes from keyboard is 0x2C which
  60     consist of keyboard address 2 and Talk against register 0.
  61
  62     Address:
  63     2:  keyboard
  64     3:  mice
  65
  66     Registers:
  67     0: application(keyobard uses this to store its data.)
  68     1: application
  69     2: application(keyboard uses this for LEDs and state of modifiers)
  70     3: status and command
  71
  72
  73 Communication
  74 -------------
  75     This is a minimum information for keyboard communication.
  76     See "Resources" for detail.
  77
  78     Signaling:
  79
  80     ~~~~____________~~||||||||||||__~~~~~_~~|||||||||||||||__~~~~
  81
  82         |800us     |  |7 Command 0|  |   |  |15-64  Data  0|Stopbit(0)
  83         +Attention |              |  |   +Startbit(1)
  84                    +Startbit(1)   |  +Tlt(140-260us)
  85                                   +stopbit(0)
  86
  87     Bit cells:
  88
  89     bit0: ______~~~
  90           65    :35us
  91
  92     bit1: ___~~~~~~
  93           35 :65us
  94
  95     bit0 low time: 60-70% of bit cell(42-91us)
  96     bit1 low time: 30-40% of bit cell(21-52us)
  97     bit cell time: 70-130us
  98     [from Apple IIgs Hardware Reference Second Edition]
  99
 100     Criterion for bit0/1:
 101     After 55us if line is low/high then bit is 0/1.
 102
 103     Attention & start bit:
 104     Host asserts low in 560-1040us then places start bit(1).
 105
 106     Tlt(Stop to Start):
 107     Bus stays high in 140-260us then device places start bit(1).
 108
 109     Global reset:
 110     Host asserts low in 2.8-5.2ms. All devices are forced to reset.
 111
 112     Send request from device(Srq):
 113     Device can request to send at commad(Global only?) stop bit.
 114     keep low for 300us to request.
 115
 116
 117 Keyboard Data(Register0)
 118     This 16bit data can contains two keycodes and two released flags.
 119     First keycode is palced in upper byte. When one keyocode is sent,
 120     lower byte is 0xFF.
 121     Release flag is 1 when key is released.
 122
 123     1514 . . . . . 8 7 6 . . . . . 0
 124      | | | | | | | | | +-+-+-+-+-+-+-   Keycode2
 125      | | | | | | | | +---------------   Released2(1 when the key is released)
 126      | +-+-+-+-+-+-+-----------------   Keycode1
 127      +-------------------------------   Released1(1 when the key is released)
 128
 129     Keycodes:
 130     Scancode consists of 7bit keycode and 1bit release flag.
 131     Device can send two keycodes at once. If just one keycode is sent
 132     keycode1 contains it and keyocode2 is 0xFF.
 133
 134     Power switch:
 135     You can read the state from PSW line(active low) however
 136     the switch has a special scancode 0x7F7F, so you can
 137     also read from Data line. It uses 0xFFFF for release scancode.
 138
 139 Keyboard LEDs & state of keys(Register2)
 140     This register hold current state of three LEDs and nine keys.
 141     The state of LEDs can be changed by sending Listen command.
 142
 143     1514 . . . . . . 7 6 5 . 3 2 1 0
 144      | | | | | | | | | | | | | | | +-   LED1(NumLock)
 145      | | | | | | | | | | | | | | +---   LED2(CapsLock)
 146      | | | | | | | | | | | | | +-----   LED3(ScrollLock)
 147      | | | | | | | | | | +-+-+-------   Reserved
 148      | | | | | | | | | +-------------   ScrollLock
 149      | | | | | | | | +---------------   NumLock
 150      | | | | | | | +-----------------   Apple/Command
 151      | | | | | | +-------------------   Option
 152      | | | | | +---------------------   Shift
 153      | | | | +-----------------------   Control
 154      | | | +-------------------------   Reset/Power
 155      | | +---------------------------   CapsLock
 156      | +-----------------------------   Delete
 157      +-------------------------------   Reserved
 158
 159 END_OF_ADB