db3f88f3af
- move IRQ control to main code (only the main code knows exactly which combination of pins is used for com2) - split one big module into multiple smaller files (easier to maintain)
82 lines
2.3 KiB
NASM
82 lines
2.3 KiB
NASM
; ***************************************************************************
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; copyright : (C) 2026 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_COM2W2_BYTEREAD_H
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#define AVR_MODULES_COM2W2_BYTEREAD_H
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.cseg
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; ---------------------------------------------------------------------------
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; @routine com2w2RecvByteWaitForQuietClk
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;
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; Wait until the clock line is consistently high for 1ms.
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;
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; @clobbers r18, r20, r22
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com2w2RecvByteWaitForQuietClk:
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ldi r18, 200
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com2w2RecvByteWaitForQuietClk_loop:
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ldi r20, 100 ; wait up to 1ms for clock high (R20, R22)
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rcall com2w2WaitForClockLowMulti10Us ; (r20, r22)
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brcs com2w2RecvByteWaitForQuietClk_waitForLow
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dec r18
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brne com2w2RecvByteWaitForQuietClk_loop
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rjmp com2w2RecvByteWaitForQuietClk_ret
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com2w2RecvByteWaitForQuietClk_waitForLow:
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ldi r20, 100 ; wait up to 1ms for clock low (R20, R22)
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rcall com2w2WaitForClockLowMulti10Us
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brcc com2w2RecvByteWaitForQuietClk_ret ; not low within 1ms, assume line is quiet
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brne com2w2RecvByteWaitForQuietClk_loop
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com2w2RecvByteWaitForQuietClk_ret:
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ret
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; ---------------------------------------------------------------------------
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; @routine com2w2RecvByte
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;
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; @return CFLAG set if byte received, cleared on error
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; @return r16 byte received
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; @clobbers r17, r18, r20, r22
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com2w2RecvByte:
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ldi r17, 8
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clr r16
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com2w2RecvByte_loop:
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ldi r20, 100 ; wait up to 1ms for clock low
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rcall com2w2WaitForClockLowMulti10Us ; (R20, R22)
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brcc com2w2RecvByte_end
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ldi r20, 100 ; wait up to 1ms for clock high
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rcall com2w2WaitForClockHighMulti10Us ; (R20, R22)
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brcc com2w2RecvByte_end
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; handle received bit
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inr r18, COM_DATA_INPUT
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andi r18, (1<<COM_DATA_PIN)
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clc
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breq com2w2RecvByte_clockData
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sec
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com2w2RecvByte_clockData:
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ror r16
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dec r17
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brne com2w2RecvByte_loop
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sec
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com2w2RecvByte_end:
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ret
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; @end
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#endif
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