212 lines
7.3 KiB
NASM
212 lines
7.3 KiB
NASM
; ***************************************************************************
|
|
; copyright : (C) 2024 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. *
|
|
; ***************************************************************************
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; @macro UART_BB_M_WAIT_FOR_PIN_LOW IN_REG_DATA, IN_PINNUM
|
|
; 0 1
|
|
; Wait for a pin to become low
|
|
; @param %0 DATA register for input pin (e.g. PINB)
|
|
; @param %1 pin number for input (e.g. PORTB1)
|
|
; @return CFLAG set if okay, clear otherwise
|
|
; @clobbers R17, R22
|
|
|
|
.macro UART_BB_M_WAIT_FOR_PIN_LOW
|
|
ldi r17, 200
|
|
l_loop:
|
|
sbis @0, @1
|
|
rjmp l_reached
|
|
Utils_WaitNanoSecs 5000, 0, r22 ; wait for 5us
|
|
dec r17
|
|
brne l_loop
|
|
clc
|
|
rjmp l_end
|
|
l_reached:
|
|
sec
|
|
l_end:
|
|
.endmacro
|
|
; @end
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; @macro UART_BB_M_WAIT_FOR_PIN_HIGH IN_REG_DATA, IN_PINNUM
|
|
; 0 1
|
|
; Wait for a pin to become high
|
|
; @param %0 DATA register for input pin (e.g. PINB)
|
|
; @param %1 pin number for input (e.g. PORTB1)
|
|
; @return CFLAG set if okay, clear otherwise
|
|
; @clobbers R17, R22
|
|
|
|
.macro UART_BB_M_WAIT_FOR_PIN_HIGH
|
|
ldi r17, 200
|
|
l_loop:
|
|
sbic @0, @1
|
|
rjmp l_reached
|
|
Utils_WaitNanoSecs 5000, 0, r22 ; wait for 5us
|
|
dec r17
|
|
brne l_loop
|
|
clc
|
|
rjmp l_end
|
|
l_reached:
|
|
sec
|
|
l_end:
|
|
.endmacro
|
|
; @end
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; @routine uartBitbang_SendByte
|
|
;
|
|
; 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
|
|
; Expects interrupts to be disabled.
|
|
;
|
|
; @param R16 byte to send
|
|
; @return CFLAG set if okay, clear otherwise
|
|
; @clobbers R16, R21, R22
|
|
|
|
uartBitbang_SendByte:
|
|
cbi COM_DATA_DDR, COM_DATA_PIN ; set DATA port as input
|
|
cbi COM_DATA_OUTPUT, COM_DATA_PIN ; disable internal pullup for DATA
|
|
ldi r21, 8 ; +1 bits left
|
|
; send startbit
|
|
sbi COM_DATA_DDR, COM_DATA_PIN ; +2 set DATA as output
|
|
cbi COM_DATA_OUTPUT, COM_DATA_PIN ; +2 set DATA low
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 1, r22 ; wait for one bit duration
|
|
; send data bits
|
|
uartBitbang_SendByte_loop: ; 9 for low bit
|
|
lsr r16 ; 1+ bit to send -> CARRY
|
|
brcs uartBitbang_SendByte_setHigh ; HI: +2, LO: +1
|
|
uartBitbang_SendByte_setLow:
|
|
sbi COM_DATA_DDR, COM_DATA_PIN ; +2 set DATA as output
|
|
cbi COM_DATA_OUTPUT, COM_DATA_PIN ; +2 set DATA low
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 11, r22
|
|
rjmp uartBitbang_SendByte_loopEnd ; +2
|
|
uartBitbang_SendByte_setHigh:
|
|
cbi COM_DATA_DDR, COM_DATA_PIN ; +2 set DATA as input, pullup R makes it ONE
|
|
nop ; +1 (to make pin change available)
|
|
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 0, r22 ; wait for half a bit length for line to safely settle
|
|
sbis COM_DATA_INPUT, COM_DATA_PIN ; +1 if no skip, +2 if skipped
|
|
rjmp uartBitbang_SendByte_error ; +2 if error (collision: we wanted line to be high but it is low)
|
|
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 11, r22
|
|
uartBitbang_SendByte_loopEnd:
|
|
dec r21 ; +1
|
|
brne uartBitbang_SendByte_loop ; +2, sum per loop: 10 cycles
|
|
; send stopbit
|
|
cbi COM_DATA_DDR, COM_DATA_PIN ; +2 set DATA as input, pullup R makes it ONE
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 0, r22 ; wait for one bit length
|
|
sec
|
|
ret
|
|
|
|
uartBitbang_SendByte_error:
|
|
clc
|
|
ret
|
|
; @end
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; @routine uartBitbangReceiveByte
|
|
;
|
|
; Read a byte.
|
|
; Expects interrupts to be disabled.
|
|
;
|
|
; @return CFLAG set if okay, clear otherwise
|
|
; @return R16 byte received
|
|
; @clobbers R16, R20, R21, R22 (R17)
|
|
|
|
uartBitbang_ReceiveByte:
|
|
cbi COM_DATA_DDR, COM_DATA_PIN ; set DATA port as input
|
|
cbi COM_DATA_OUTPUT, COM_DATA_PIN ; disable internal pullup for RXD
|
|
ldi r21, 8 ; bits left
|
|
clr r20 ; byte currently receiving
|
|
; wait for startbit
|
|
rcall uartBitbang_WaitForDataLow ; (R17, R22)
|
|
brcc uartBitbang_ReceiveByte_error
|
|
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 10, r22 ; goto middle of startbit to maximize sync stability
|
|
uartBitbang_ReceiveByte_loop:
|
|
Utils_WaitNanoSecs COM_BIT_LENGTH, 8, r22 ; 8 cycles used in the complete loop between waits
|
|
sec ; +1
|
|
sbic COM_DATA_INPUT, COM_DATA_PIN ; LOW: +2, HIGH: +1
|
|
rjmp uartBitbang_ReceiveByte_shiftIn ; HIGH: +2, rjmp, use set CFLAG
|
|
clc ; LOW: +1
|
|
uartBitbang_ReceiveByte_shiftIn:
|
|
ror r20 ; +1
|
|
dec r21 ; +1
|
|
brne uartBitbang_ReceiveByte_loop ; +2, sum per loop: 8 cycles
|
|
rcall uartBitbang_WaitForDataHigh ; wait for start of stopbit
|
|
brcc uartBitbang_ReceiveByte_error
|
|
mov r16, r20
|
|
sec
|
|
ret
|
|
uartBitbang_ReceiveByte_error:
|
|
clc
|
|
ret
|
|
; @end
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; @routine uartBitbang_WaitForDataLow
|
|
;
|
|
; Wait up to 1ms for data pin to become low
|
|
; @return CFLAG set if okay, clear otherwise
|
|
; @clobbers R17, R22
|
|
|
|
uartBitbang_WaitForDataLow:
|
|
cbi COM_DATA_DDR, COM_DATA_PIN ; set DATA port as input
|
|
cbi COM_DATA_OUTPUT, COM_DATA_PIN ; disable internal pullup for TXD
|
|
UART_BB_M_WAIT_FOR_PIN_LOW COM_DATA_INPUT, COM_DATA_PIN
|
|
ret
|
|
; @end
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; @routine uartBitbang_WaitForDataHigh
|
|
;
|
|
; Wait up to 1ms for data pin to become high
|
|
; @return CFLAG set if okay, clear otherwise
|
|
; @clobbers R17, R22
|
|
|
|
uartBitbang_WaitForDataHigh:
|
|
cbi COM_DATA_DDR, COM_DATA_PIN ; set DATA port as input
|
|
cbi COM_DATA_OUTPUT, COM_DATA_PIN ; disable internal pullup for TXD
|
|
UART_BB_M_WAIT_FOR_PIN_HIGH COM_DATA_INPUT, COM_DATA_PIN
|
|
ret
|
|
; @end
|
|
|
|
|
|
|
|
; ---------------------------------------------------------------------------
|
|
; @routine uartBitbang_WaitForAttnHigh
|
|
;
|
|
; Wait up to 1ms for data pin to become high
|
|
; @return CFLAG set if okay, clear otherwise
|
|
; @clobbers R17, R22
|
|
|
|
uartBitbang_WaitForAttnHigh:
|
|
cbi COM_ATTN_DDR, COM_ATTN_PIN ; set ATTN port as input
|
|
cbi COM_ATTN_OUTPUT, COM_ATTN_PIN ; disable internal pullup for ATTN
|
|
UART_BB_M_WAIT_FOR_PIN_HIGH COM_ATTN_INPUT, COM_ATTN_PIN
|
|
ret
|
|
; @end
|
|
|
|
|
|
|
|
|
|
|