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@@ -199,24 +199,48 @@ static inline bool read_bit(void) |
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{ |
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// ADB Bit Cells |
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// |
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// bit0: ______~~~ |
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// 65 :35us |
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// bit cell time: 70-130us |
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// low part of bit0: 60-70% of bit cell |
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// low part of bit1: 30-40% of bit cell |
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// |
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// bit1: ___~~~~~~ |
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// 35 :65us |
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// bit cell time 70us 130us |
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// -------------------------------------------- |
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// low part of bit0 42-49 78-91 |
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// high part of bit0 21-28 39-52 |
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// low part of bit1 21-28 39-52 |
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// high part of bit1 42-49 78-91 |
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// |
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// bit0 low time: 60-70% of bit cell(42-91us) |
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// bit1 low time: 30-40% of bit cell(21-52us) |
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// bit cell time: 70-130us |
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// [from Apple IIgs Hardware Reference Second Edition] |
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// |
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// After 55us if data line is low/high then bit is 0/1. |
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// Too simple to rely on? |
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// bit0: |
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// 70us bit cell: |
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// ____________~~~~~~ |
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// 42-49 21-28 |
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// |
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// 130us bit cell: |
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// ____________~~~~~~ |
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// 78-91 39-52 |
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// |
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// bit1: |
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// 70us bit cell: |
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// ______~~~~~~~~~~~~ |
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// 21-28 42-49 |
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// |
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// 130us bit cell: |
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// ______~~~~~~~~~~~~ |
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// 39-52 78-91 |
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// |
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// read: |
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// ________|~~~~~~~~~ |
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// 55us |
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// Read data line after 55us. If data line is low/high then bit is 0/1. |
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// This method might not work at <90us bit cell time. |
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// |
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// [from Apple IIgs Hardware Reference Second Edition] |
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bool bit; |
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wait_data_lo(75); // wait the beginning of bit cell |
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wait_data_lo(75); // wait the start of bit cell at least 130ms(55+0+75) |
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_delay_us(55); |
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bit = data_in(); |
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wait_data_hi(36); // wait high part of bit cell |
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wait_data_hi(36); // wait high part of bit cell at least 91ms(55+36) |
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return bit; |
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} |
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@@ -258,7 +282,7 @@ Resources |
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--------- |
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ADB - The Untold Story: Space Aliens Ate My Mouse |
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http://developer.apple.com/legacy/mac/library/#technotes/hw/hw_01.html |
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Apple IIgs Hardware Reference Second Edition [p80(Chapter6 p121)] |
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Apple IIgs Hardware Reference Second Edition [Chapter6 p121] |
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ftp://ftp.apple.asimov.net/pub/apple_II/documentation/Apple%20IIgs%20Hardware%20Reference.pdf |
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ADB Keycode |
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http://72.0.193.250/Documentation/macppc/adbkeycodes/ |
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@@ -376,9 +400,9 @@ Communication |
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Global reset: |
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Host asserts low in 2.8-5.2ms. All devices are forced to reset. |
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Send request from device(Srq): |
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Service request from device(Srq): |
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Device can request to send at commad(Global only?) stop bit. |
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keep low for 300us to request. |
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Requesting device keeps low for 140-260us at stop bit of command. |
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Keyboard Data(Register0) |