234 lines
6.7 KiB
NASM
234 lines
6.7 KiB
NASM
; ***************************************************************************
|
|
; copyright : (C) 2023 by Martin Preuss
|
|
; email : martin@libchipcard.de
|
|
;
|
|
; ***************************************************************************
|
|
; * This file is part of the project "AqHome". *
|
|
; * Please see toplevel file COPYING of that project for license details. *
|
|
; ***************************************************************************
|
|
|
|
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; com2SendByte
|
|
;
|
|
; Send a byte.
|
|
; We only set the data pin to low at the beginning for the startbit. After that
|
|
; we only change the pin direction (e.g. input vs output):
|
|
; - for 0 bit: set DDR to output, forcing the data line low
|
|
; - for 1 bit: set DDR to input, letting the external pullup R pull the data line to HIGH
|
|
; since the output pin is still set to 0 the internal pullup is disabled
|
|
; IN:
|
|
; - R16: byte to send
|
|
; OUT:
|
|
; - CFLAG: set if okay, clear otherwise
|
|
; MODIFIED REGS: R16, R21, R22
|
|
|
|
com2SendByte:
|
|
ldi r21, 8 ; +1 bits left
|
|
; send startbit
|
|
cbi COM_PORT_DATA, COM_PINNUM_DATA ; +2 set DATA low
|
|
sbi COM_DDR_DATA, COM_PINNUM_DATA ; +2 set DATA as output
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 5, r22 ; wait for one bit duration
|
|
; send data bits
|
|
com2SendByte_loop: ; 9 for low bit
|
|
lsr r16 ; 1+ bit to send -> CARRY
|
|
brcs com2SendByte_setHigh ; HI: +2, LO: +1
|
|
com2SendByte_setLow:
|
|
sbi COM_DDR_DATA, COM_PINNUM_DATA ; +2 set DATA as output
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 9, r22
|
|
rjmp com2SendByte_loopEnd ; +2
|
|
com2SendByte_setHigh:
|
|
cbi COM_DDR_DATA, COM_PINNUM_DATA ; +2 set DATA as input, pullup R makes it ONE
|
|
nop ; +1 (to make pin change available)
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH/2, 11, r22 ; wait for half a bit length for line to safely settle
|
|
sbis COM_PIN_DATA, COM_PINNUM_DATA ; +1 if no skip, +2 if skipped
|
|
rjmp com2SendByte_error ; +2 if error (collision: we wanted line to be high but it is low)
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH/2, 0, r22
|
|
com2SendByte_loopEnd:
|
|
dec r21 ; +1
|
|
brne com2SendByte_loop ; +2, sum per loop: 10 cycles
|
|
; send stopbit
|
|
cbi COM_DDR_DATA, COM_PINNUM_DATA ; +2 set DATA as input, pullup R makes it ONE
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 4, r22 ; wait for one bit length
|
|
sec
|
|
ret
|
|
|
|
com2SendByte_error:
|
|
clc
|
|
ret
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; com2ReceiveByte
|
|
;
|
|
; Receive a byte.
|
|
;
|
|
; IN:
|
|
; - nothing
|
|
; OUT:
|
|
; - CFLAG: set if okay, clear otherwise
|
|
; - R16: byte read (if CFLAG set)
|
|
; MODIFIED REGS: R16, R20, R21, R22 (R17)
|
|
|
|
com2ReceiveByte:
|
|
cbi COM_DDR_DATA, COM_PINNUM_DATA ; set DATA port as input
|
|
cbi COM_PORT_DATA, COM_PINNUM_DATA ; disable internal pullup for DATA
|
|
|
|
ldi r21, 8 ; bits left
|
|
clr r20 ; byte currently receiving
|
|
; wait for startbit
|
|
rcall com2WaitForDataLow ; (R17)
|
|
brcc com2ReceiveByte_error
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH/2, 5, r22 ; goto middle of startbit to maximize sync stability
|
|
com2ReceiveByte_loop:
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 8, r22 ; 8 cycles used in the complete loop between waits
|
|
sec ; +1
|
|
sbic COM_PIN_DATA, COM_PINNUM_DATA ; LOW: +2, HIGH: +1
|
|
rjmp com2ReceiveByte_shiftIn ; HIGH: +2, rjmp, use set CFLAG
|
|
clc ; LOW: +1
|
|
com2ReceiveByte_shiftIn:
|
|
ror r20 ; +1
|
|
dec r21 ; +1
|
|
brne com2ReceiveByte_loop ; +2, sum per loop: 8 cycles
|
|
rcall com2WaitForDataHigh ; wait for start of stopbit
|
|
brcc com2ReceiveByte_error
|
|
mov r16, r20
|
|
sec
|
|
ret
|
|
com2ReceiveByte_error:
|
|
clc
|
|
ret
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; com2WaitForDataLow
|
|
;
|
|
; Waits up to COM2_MAXWAIT_US loops for low data line
|
|
; IN:
|
|
; OUT:
|
|
; - CFLAG: set if okay, clear otherwise
|
|
; MODIFIED REGISTERS: r17, r22
|
|
|
|
com2WaitForDataLow:
|
|
ldi r17, COM2_MAXWAIT_US
|
|
|
|
com2WaitForDataLow_loop:
|
|
sbis COM_PIN_DATA, COM_PINNUM_DATA
|
|
rjmp com2WaitForDataLow_done
|
|
rcall com2WaitFor1000ns
|
|
dec r17
|
|
brne com2WaitForDataLow_loop
|
|
clc ; timeout
|
|
ret
|
|
|
|
com2WaitForDataLow_done:
|
|
sec ; ok
|
|
ret
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; com2WaitForDataHigh
|
|
;
|
|
; Waits up to COM2_MAXWAIT_US loops for high data line
|
|
; IN:
|
|
; OUT:
|
|
; - CFLAG: set if okay, clear otherwise
|
|
; MODIFIED REGISTERS: r17, r22, X
|
|
|
|
com2WaitForDataHigh:
|
|
ldi r17, COM2_MAXWAIT_US
|
|
|
|
com2WaitForDataHigh_loop:
|
|
sbic COM_PIN_DATA, COM_PINNUM_DATA
|
|
rjmp com2WaitForDataHigh_done
|
|
rcall com2WaitFor1000ns
|
|
dec r17
|
|
brne com2WaitForDataHigh_loop
|
|
clc ; timeout
|
|
ret
|
|
|
|
com2WaitForDataHigh_done:
|
|
sec ; ok
|
|
ret
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; com2WaitForAttnHigh
|
|
;
|
|
; Waits up to COM2_MAXWAIT_US loops for high ATTN line
|
|
; IN:
|
|
; OUT:
|
|
; - CFLAG: set if okay, clear otherwise
|
|
; MODIFIED REGISTERS: r17, r22, X
|
|
|
|
com2WaitForAttnHigh:
|
|
ldi r17, COM2_MAXWAIT_US
|
|
|
|
com2WaitForAttnHigh_loop:
|
|
sbic COM_PIN_ATTN, COM_PINNUM_ATTN
|
|
rjmp com2WaitForAttnHigh_done
|
|
rcall com2WaitFor1000ns
|
|
dec r17
|
|
brne com2WaitForAttnHigh_loop
|
|
clc ; timeout
|
|
ret
|
|
|
|
com2WaitForAttnHigh_done:
|
|
sec ; ok
|
|
ret
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; com2WaitForDataState1ms
|
|
;
|
|
; Waits up to COM2_MAXWAIT_US loops for high ATTN line
|
|
; IN:
|
|
; OUT:
|
|
; - CFLAG: set if state reached, cleared otherwise
|
|
; REGS: R24 (R22)
|
|
|
|
com2WaitForDataState1ms:
|
|
ldi r24, 100
|
|
com2WaitForDataState1ms_loop:
|
|
push r17
|
|
in r17, COM_PIN_DATA
|
|
eor r17, r16
|
|
andi r17, (1<<COM_PINNUM_DATA)
|
|
pop r17
|
|
breq com2WaitForDataState1ms_stateReached
|
|
Utils_WaitNanoSecs 10000, 0, r22 ; wait for 10us
|
|
dec r24
|
|
brne com2WaitForDataState1ms_loop
|
|
clc
|
|
ret
|
|
com2WaitForDataState1ms_stateReached:
|
|
sec
|
|
ret
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; comWaitFor1000ns
|
|
;
|
|
; Waits for 1000 nanoseconds.
|
|
; IN:
|
|
; OUT:
|
|
; - CFLAG: set if okay, clear otherwise
|
|
; REGS: r22
|
|
|
|
com2WaitFor1000ns:
|
|
Utils_WaitNanoSecs 1000, 7, r22 ; wait for 1000 nanosecs (minus 3 cycles for rcall, 4 for ret)
|
|
ret
|
|
|
|
|
|
|
|
|