59 lines
1.4 KiB
NASM
59 lines
1.4 KiB
NASM
; ***************************************************************************
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; copyright : (C) 2025 by Martin Preuss
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; email : martin@libchipcard.de
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;
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; ***************************************************************************
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; * This file is part of the project "AqHome". *
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; * Please see toplevel file COPYING of that project for license details. *
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; ***************************************************************************
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#ifndef AVR_MODULES_UART_HW2_SYNC_H
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#define AVR_MODULES_UART_HW2_SYNC_H
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.dseg
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.cseg
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; sync length is 1000 us, so this should return:
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; - 125 for 1 MHz
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; - 1000 for 8 MHz
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syncRecv:
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syncRecv_waitForHigh:
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sbis COM_DATA0_INPUT, COM_DATA0_PIN
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rjmp syncRecv_waitForHigh
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clr r24
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clr r25
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syncRecv_waitForLow:
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sbic COM_DATA0_INPUT, COM_DATA0_PIN
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rjmp syncRecv_waitForLow
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syncRecv_countLow: ; total: +8 per loop
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sbic COM_DATA0_INPUT, COM_DATA0_PIN ; +1 if noskip, +2 if skip
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rjmp syncRecv_countDone ; +2, total: +2 every loop, +3 in last loop
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adiw r25:r24, 1 ; +1
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breq syncRecv_countError ; +1 if not 0, +2 if 0
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nop ; +1
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nop ; +1
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rjmp syncRecv_countLow ; +2
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syncRecv_countError:
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clr r24
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clr r25
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syncRecv_countDone:
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ret
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; @end
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#endif
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