darkkirb/qmk_firmware
1
0
Fork 0
forked from mirrors/qmk_firmware
Code Issues Pull requests Projects Releases Packages Wiki Activity

Fix comment of ADB signaling.

Browse source
This commit is contained in:
tmk 2012-12-05 13:38:16 +09:00
parent de7b46cd7d
commit 9bdd89980f
1 changed files with 40 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

56
protocol/adb.c
View file

@ -199,24 +199,48 @@ static inline bool read_bit(void)
{
// ADB 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]
// low part of bit0: 60-70% of bit cell
// low part of bit1: 30-40% of bit cell
//
// After 55us if data line is low/high then bit is 0/1.
// Too simple to rely on?
// bit cell time 70us 130us
// --------------------------------------------
// low part of bit0 42-49 78-91
// high part of bit0 21-28 39-52
// low part of bit1 21-28 39-52
// high part of bit1 42-49 78-91
//
//
// bit0:
// 70us bit cell:
// ____________~~~~~~
// 42-49 21-28
//
// 130us bit cell:
// ____________~~~~~~
// 78-91 39-52
//
// bit1:
// 70us bit cell:
// ______~~~~~~~~~~~~
// 21-28 42-49
//
// 130us bit cell:
// ______~~~~~~~~~~~~
// 39-52 78-91
//
// read:
// ________|~~~~~~~~~
// 55us
// Read data line after 55us. If data line is low/high then bit is 0/1.
// This method might not work at <90us bit cell time.
//
// [from Apple IIgs Hardware Reference Second Edition]
bool bit;
wait_data_lo(75); // wait the beginning of bit cell
wait_data_lo(75); // wait the start of bit cell at least 130ms(55+0+75)
_delay_us(55);
bit = data_in();
wait_data_hi(36); // wait high part of bit cell
wait_data_hi(36); // wait high part of bit cell at least 91ms(55+36)
return bit;
}
@ -258,7 +282,7 @@ 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)]
Apple IIgs Hardware Reference Second Edition [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/
@ -376,9 +400,9 @@ Communication
Global reset:
Host asserts low in 2.8-5.2ms. All devices are forced to reset.
Send request from device(Srq):
Service request from device(Srq):
Device can request to send at commad(Global only?) stop bit.
keep low for 300us to request.
Requesting device keeps low for 140-260us at stop bit of command.
Keyboard Data(Register0)