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- 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
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