Files
aqhomecontrol/avr/modules/flash/io_bitbang.asm
2025-05-18 00:58:11 +02:00

394 lines
12 KiB
NASM

; ***************************************************************************
; copyright : (C) 2025 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. *
; ***************************************************************************
; ***************************************************************************
; macros
; ---------------------------------------------------------------------------
; @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 (up to 1ms)
; @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
; ***************************************************************************
; code
.cseg
; ---------------------------------------------------------------------------
; @routine ioRawInit
; Init raw message subsystem.
;
; @clobbers none
ioRawInit:
; setup pins and interrupts
cbi COM_DATA_DDR, COM_DATA_PIN ; set DATA port as input
cbi COM_DATA_OUTPUT, COM_DATA_PIN ; disable internal pullup for TXD
cbi COM_ATTN_DDR, COM_ATTN_PIN ; set ATTN port as input
cbi COM_ATTN_OUTPUT, COM_ATTN_PIN ; disable internal pullup for ATTN
ret
;@end
; ---------------------------------------------------------------------------
; @routine ioRawSendMsg
; Send a message
;
; @clobbers X (R16, R17, R21, R22)
ioRawSendMsg:
ioRawSendMsg_loop:
ldi r16, 0xff ; expect ATTN high
ldi r17, 10
rcall ioWaitForAttnState100ms ; wait for up to 1s
brcs ioRawSendMsg_attnHigh
ret
ioRawSendMsg_attnHigh:
ldi xl, LOW(flashSendBuffer)
ldi xh, HIGH(flashSendBuffer)
rcall ioRawSendPacket ; R16, R22 (R17, R21, X)
brcc ioRawSendMsg_loop
ret
; @end
; ---------------------------------------------------------------------------
; @routine ioRawWaitForValidMsg
;
; Wait for valid incoming msg
;
; First waits for ATTN line to go high (released) then wait for ATTN
; line to go low. This way we will only start listening at the beginning of
; a message.
;
; @return CFLAG set if okay (packet received), cleared on error
; @clobbers: r16, r17 (r18, r19, r20, r21, r22, X)
ioRawWaitForValidMsg:
ldi r16, 0xff ; expect ATTN high
ldi r17, 100
rcall ioWaitForAttnState100ms ; wait for up to 10s
brcc ioRawWaitForValidMsg_end ; ATTN not high, exit
ldi r16, 0 ; expect ATTN low
ldi r17, 100
rcall ioWaitForAttnState100ms ; wait for up to 10s
brcs ioRawWaitForValidMsg_attnLow
ret
ioRawWaitForValidMsg_attnLow:
ldi xl, LOW(flashRecvBuffer)
ldi xh, HIGH(flashRecvBuffer)
ldi r16, NET_MAINTENANCE_ADDR
ldi r17, FLASH_RECVBUFFER_MAXLEN-3
rcall ioRawReceivePacketIntoBuffer
brcs ioRawWaitForValidMsg_packetReceived
; wait until ATTN is high (up to 10s)
ldi r16, 0xff ; expect ATTN high
ldi r17, 100
rcall ioWaitForAttnState100ms ; wait for up to 10s
clc
ret
ioRawWaitForValidMsg_packetReceived:
ldi r16, 0xff ; expect ATTN high
ldi r17, 100
rcall ioWaitForAttnState100ms ; wait for up to 10s
brcc ioRawWaitForValidMsg_end
ldi xl, LOW(flashRecvBuffer)
ldi xh, HIGH(flashRecvBuffer)
rcall NETMSG_CheckMessageInBuffer
ioRawWaitForValidMsg_end:
ret
; @end
; ---------------------------------------------------------------------------
; @routine ioRawReceivePacketIntoBuffer
;
; Receive a packet into buffer pointed to by X.
; Expects interrupts to be disabled.
;
; @param R16 COM address to listen to
; @param R17 maximum value for accepted msg data (i.e. buffersize minus 3)
; @param X buffer to receive to
; @return CFLAG set if okay (packet received), cleared on error
; @clobbers: r16, r17, r18, X (r19, r20, r21, r22)
ioRawReceivePacketIntoBuffer:
mov r18, r17
push r16
; read destination address
rcall ioRawReceiveByte ; read byte (R16, R17, R20, R21, R22)
pop r17 ; pop from R16 to R17
brcc ioRawReceivePacketIntoBuffer_error
#ifndef COM_ACCEPT_ALL_DEST ; accept every destination address
; compare destination address (accept "FF" and own address)
cp r16, r17
breq ioRawReceivePacketIntoBuffer_acceptAddr
cpi r16, 0xff
breq ioRawReceivePacketIntoBuffer_acceptAddr
ldi r16, COM2_ERROR_NOTFORME
rjmp ioRawReceivePacketIntoBuffer_error ; clc/ret
#endif
ioRawReceivePacketIntoBuffer_acceptAddr:
st X+, r16 ; store dest address, lock buffer
; read msg length
rcall ioRawReceiveByte ; read packet length (R16, R17, R20, R21, R22)
brcc ioRawReceivePacketIntoBuffer_error
st X+, r16
cp r16, r18 ; (COM2_BUFFER_SIZE-3)
brcc ioRawReceivePacketIntoBuffer_error ; packet too long
inc r16 ; account for checksum byte
mov r17, r16
ioRawReceivePacketIntoBuffer_loop:
push r17
rcall ioRawReceiveByte ; read byte (R16, R17, R20, R21, R22)
pop r17
brcc ioRawReceivePacketIntoBuffer_error
st X+, r16
dec r17
brne ioRawReceivePacketIntoBuffer_loop
sec
ret
ioRawReceivePacketIntoBuffer_error:
clc
ret
; @end
; ---------------------------------------------------------------------------
; @routine ioRawReceiveByte
;
; 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)
ioRawReceiveByte:
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 ioRawWaitForDataLow ; (R17, R22)
brcc ioRawReceiveByte_error
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 10, r22 ; goto middle of startbit to maximize sync stability
ioRawReceiveByte_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 ioRawReceiveByte_shiftIn ; HIGH: +2, rjmp, use set CFLAG
clc ; LOW: +1
ioRawReceiveByte_shiftIn:
ror r20 ; +1
dec r21 ; +1
brne ioRawReceiveByte_loop ; +2, sum per loop: 8 cycles
rcall ioRawWaitForDataHigh ; wait for start of stopbit
brcc ioRawReceiveByte_error
mov r16, r20
sec
ret
ioRawReceiveByte_error:
clc
ret
; @end
; ---------------------------------------------------------------------------
; @routine ioRawSendPacket
;
; Send packet over wire, handle ATTN line.
;
; @param X ptr to buffer to send
; @return CFLAGS set if okay, cleared otherwise (errorcode in R16)
; @clobbers R16, R22 (R17, R21, X)
ioRawSendPacket:
rcall ioRawAcquireBus ; (none)
brcc ioRawSendPacket_ret
rcall ioRawWaitForOneBitLength ; wait for one bit duration (R22)
rcall ioRawWaitForOneBitLength ; wait for one bit duration (R22)
adiw xh:xl, NETMSG_OFFS_MSGLEN
ld r17, X
sbiw xh:xl, NETMSG_OFFS_MSGLEN
inc r17 ; account for dest addr
inc r17 ; account for msglen byte
inc r17 ; account for crc byte
ioRawSendPacket_loop:
ld r16, X+
rcall ioRawSendByte ; send byte (R16, R21, R22)
brcc ioRawSendPacket_releaseBusRet
dec r17
brne ioRawSendPacket_loop
sec
ioRawSendPacket_releaseBusRet:
cbi COM_ATTN_DDR, COM_ATTN_PIN ; release ATTN line (by setting direction to IN)
ioRawSendPacket_ret:
ret
; @end
; ---------------------------------------------------------------------------
; @routine ioRawSendByte
;
; 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
ioRawSendByte:
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
ioRawSendByte_loop: ; 9 for low bit
lsr r16 ; 1+ bit to send -> CARRY
brcs ioRawSendByte_setHigh ; HI: +2, LO: +1
ioRawSendByte_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 ioRawSendByte_loopEnd ; +2
ioRawSendByte_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 ioRawSendByte_error ; +2 if error (collision: we wanted line to be high but it is low)
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 11, r22
ioRawSendByte_loopEnd:
dec r21 ; +1
brne ioRawSendByte_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
ioRawSendByte_error:
clc
ret
; @end
; ---------------------------------------------------------------------------
; @routine ioRawWaitForDataLow
;
; Wait up to 1ms for data pin to become low
; @return CFLAG set if okay, clear otherwise
; @clobbers R17, R22
ioRawWaitForDataLow:
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 ioRawWaitForDataHigh
;
; Wait up to 1ms for data pin to become high
; @return CFLAG set if okay, clear otherwise
; @clobbers R17, R22
ioRawWaitForDataHigh:
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