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     ADB female socket from the front:
  27     __________
  28     |        | <--- top
  29     | 4o  o3 |
  30     |2o    o1|
  31     |   ==   |
  32     |________| <--- bottom
  33       |    |   <--- 4pins
  34
  35
  36     ADB female socket from bottom:
  37
  38     ========== <--- front
  39     |        |
  40     |        |
  41     |2o    o1|
  42     |4o    o3|
  43     ---------- <--- back
  44
  45     1: Data
  46     2: Power SW(low when press Power key)
  47     3: Vcc(5V)
  48     4: GND
  49
  50
  51
  52 Commands
  53 --------
  54     ADB command is 1byte and consists of 4bit-address, 2bit-command
  55     type and 2bit-register. The commands are always sent by Host.
  56
  57     Command format:
  58     7 6 5 4 3 2 1 0
  59     | | | |------------ address
  60             | |-------- command type
  61                 | |---- register
  62
  63     bits                commands
  64     ------------------------------------------------------
  65     - - - - 0 0 0 0     Send Request(reset all devices)
  66     A A A A 0 0 0 1     Flush(reset a device)
  67     - - - - 0 0 1 0     Reserved
  68     - - - - 0 0 1 1     Reserved
  69     - - - - 0 1 - -     Reserved
  70     A A A A 1 0 R R     Listen(write to a device)
  71     A A A A 1 1 R R     Talk(read from a device)
  72
  73     The command to read keycodes from keyboard is 0x2C which
  74     consist of keyboard address 2 and Talk against register 0.
  75
  76     Address:
  77     2:  keyboard
  78     3:  mice
  79
  80     Registers:
  81     0: application(keyobard uses this to store its data.)
  82     1: application
  83     2: application(keyboard uses this for LEDs and state of modifiers)
  84     3: status and command
  85
  86
  87 Communication
  88 -------------
  89     This is a minimum information for keyboard communication.
  90     See "Resources" for detail.
  91
  92     Signaling:
  93
  94     ~~~~____________~~||||||||||||__~~~~~_~~|||||||||||||||__~~~~
  95
  96         |800us     |  |7 Command 0|  |   |  |15-64  Data  0|Stopbit(0)
  97         +Attention |              |  |   +Startbit(1)
  98                    +Startbit(1)   |  +Tlt(140-260us)
  99                                   +stopbit(0)
 100
 101     Bit cells:
 102
 103     bit0: ______~~~
 104           65    :35us
 105
 106     bit1: ___~~~~~~
 107           35 :65us
 108
 109     bit0 low time: 60-70% of bit cell(42-91us)
 110     bit1 low time: 30-40% of bit cell(21-52us)
 111     bit cell time: 70-130us
 112     [from Apple IIgs Hardware Reference Second Edition]
 113
 114     Criterion for bit0/1:
 115     After 55us if line is low/high then bit is 0/1.
 116
 117     Attention & start bit:
 118     Host asserts low in 560-1040us then places start bit(1).
 119
 120     Tlt(Stop to Start):
 121     Bus stays high in 140-260us then device places start bit(1).
 122
 123     Global reset:
 124     Host asserts low in 2.8-5.2ms. All devices are forced to reset.
 125
 126     Send request from device(Srq):
 127     Device can request to send at commad(Global only?) stop bit.
 128     keep low for 300us to request.
 129
 130
 131 Keyboard Data(Register0)
 132     This 16bit data can contains two keycodes and two released flags.
 133     First keycode is palced in upper byte. When one keyocode is sent,
 134     lower byte is 0xFF.
 135     Release flag is 1 when key is released.
 136
 137     1514 . . . . . 8 7 6 . . . . . 0
 138      | | | | | | | | | +-+-+-+-+-+-+-   Keycode2
 139      | | | | | | | | +---------------   Released2(1 when the key is released)
 140      | +-+-+-+-+-+-+-----------------   Keycode1
 141      +-------------------------------   Released1(1 when the key is released)
 142
 143     Keycodes:
 144     Scancode consists of 7bit keycode and 1bit release flag.
 145     Device can send two keycodes at once. If just one keycode is sent
 146     keycode1 contains it and keyocode2 is 0xFF.
 147
 148     Power switch:
 149     You can read the state from PSW line(active low) however
 150     the switch has a special scancode 0x7F7F, so you can
 151     also read from Data line. It uses 0xFFFF for release scancode.
 152
 153 Keyboard LEDs & state of keys(Register2)
 154     This register hold current state of three LEDs and nine keys.
 155     The state of LEDs can be changed by sending Listen command.
 156
 157     1514 . . . . . . 7 6 5 . 3 2 1 0
 158      | | | | | | | | | | | | | | | +-   LED1(NumLock)
 159      | | | | | | | | | | | | | | +---   LED2(CapsLock)
 160      | | | | | | | | | | | | | +-----   LED3(ScrollLock)
 161      | | | | | | | | | | +-+-+-------   Reserved
 162      | | | | | | | | | +-------------   ScrollLock
 163      | | | | | | | | +---------------   NumLock
 164      | | | | | | | +-----------------   Apple/Command
 165      | | | | | | +-------------------   Option
 166      | | | | | +---------------------   Shift
 167      | | | | +-----------------------   Control
 168      | | | +-------------------------   Reset/Power
 169      | | +---------------------------   CapsLock
 170      | +-----------------------------   Delete
 171      +-------------------------------   Reserved
 172
 173 END_OF_ADB