diff options
Diffstat (limited to 'protocol/adb.c')
| -rw-r--r-- | protocol/adb.c | 54 |
1 files changed, 39 insertions, 15 deletions
diff --git a/protocol/adb.c b/protocol/adb.c index 9e8d76832d..a92e81f1f6 100644 --- a/protocol/adb.c +++ b/protocol/adb.c @@ -199,24 +199,48 @@ static inline bool read_bit(void) { // ADB Bit Cells // - // bit0: ______~~~ - // 65 :35us + // bit cell time: 70-130us + // low part of bit0: 60-70% of bit cell + // low part of bit1: 30-40% of bit cell // - // bit1: ___~~~~~~ - // 35 :65us + // 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 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] // - // After 55us if data line is low/high then bit is 0/1. - // Too simple to rely on? + // 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) |