martin/aqhomecontrol
Public Access
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

avr: improved protocol timing for COM2.

Browse Source 
- increased waiting time after lowering ATTN line
- lengthten stop bit for cleaner frames (now recognized by PulseView)
- count "NOTFORME" conditions
- introduce definition COM_HALFBIT_LENGTH (I dont' trust value calculations
  in avrasm)
This commit is contained in:
Martin Preuss
2024-09-29 14:59:19 +02:00
parent b93ead5e5f
commit 5767c1307d
9 changed files with 88 additions and 30 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
avr/modules/com2/lowlevel.asm
View File

@@ -31,7 +31,7 @@ com2SendByte:
; 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
Utils_WaitNanoSecs COM_BIT_LENGTH, 1, r22 ; wait for one bit duration
; send data bits
com2SendByte_loop: ; 9 for low bit
lsr r16 ; 1+ bit to send -> CARRY
@@ -43,16 +43,16 @@ com2SendByte_setLow:
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
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 0, 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
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 11, 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
Utils_WaitNanoSecs COM_BIT_LENGTH, 0, r22 ; wait for one bit length
rjmp com2LowLevelSecRet
com2SendByte_error:
@@ -81,7 +81,7 @@ com2ReceiveByte:
; wait for startbit
rcall com2WaitForDataLow ; (R16, R17, R22)
brcc com2ReceiveByte_error
Utils_WaitNanoSecs COM_BIT_LENGTH/2, 5, r22 ; goto middle of startbit to maximize sync stability
Utils_WaitNanoSecs COM_HALFBIT_LENGTH, 10, 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
@@ -149,7 +149,7 @@ com2WaitForAttnHigh:
; ---------------------------------------------------------------------------
; com2WaitForDataState1ms
;
; Waits up to 1ms for high DATA line
; Waits up to 500us for high DATA line
; IN:
; - R16: state to wait for (00 for low, 0xff for high)
; OUT:
@@ -163,12 +163,14 @@ com2WaitForDataState1ms_loop:
eor r22, r16
andi r22, (1<<COM_PINNUM_DATA)
breq com2WaitForDataState1ms_stateReached
rcall Utils_WaitFor10MicroSecs ; wait for 10us (R22)
; rcall Utils_WaitFor10MicroSecs ; wait for 10us (R22)
Utils_WaitNanoSecs 5000, 0, r22
dec r17
brne com2WaitForDataState1ms_loop
rjmp com2LowLevelClcRet
com2WaitForDataState1ms_stateReached:
rjmp com2LowLevelSecRet
sec
ret