waitcnt asm
TomS
Posts: 128
I'm having a problem with waitcnt in assembly that I can't figure out. The loop repeats in about 20 seconds no matter what I assign to LoopTime. The "transmit" code seems to work fine and was taken from FullDuplexSerial and extensively modified.
Here's my code:
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Tom
Here's my code:
{{Serial_tx_asm.spin
Tom Smuts
}}
VAR
long cog
long tx_pin '6 contiguous longs (Don't change order or add/delete var's)
long desc_ptr
long ip_ptr
long dbm_ptr
long pcent_ptr
long bit_ticks
PUB Start(txpin, descPntr, ipPntr, dBmPntr, pcentPntr, baudrate) : okay
stop
longmove(@tx_pin, @txpin, 5) 'Fill var's from passed parms
bit_ticks := clkfreq / baudrate 'bit_ticks = num clks per bit
okay := cog := cognew(@entry, @tx_pin) + 1
PUB Stop
if cog
cogstop(cog~ - 1)
DAT
entry org 0
mov t1, par 'get structure address
rdlong t2, t1 'get tx_pin
mov txmask, #1
shl txmask, t2 'txmask defines transmit pin
add t1, #4 'get desc_ptr
rdlong descptr, t1
add t1, #4 'get ip_ptr
rdlong ipptr, t1
add t1, #4 'get dbm_ptr
rdlong dbmptr, t1
add t1, #4 'get pcent_ptr
rdlong pcentptr, t1
add t1, #4 'get bit_ticks
rdlong bitticks, t1
mov rxtxmode, #0 'mode = 0
test rxtxmode, #%100 wz 'init tx pin according to mode
test rxtxmode, #%010 wc
or outa, txmask
or dira, txmask
'----------------------------------------------------------------------------------------------
loop_start
'----------------------------------------------------------------------------------------------
'Line 1
mov bytecntr, descptr
call #transmit
mov bytecntr, ipptr
call #transmit
'wait
mov time, cnt
add time, LoopTime
waitcnt time, LoopTime
jmp #loop_start
'----------------------------------------------------------------------------------------------
'----------------------------------------------------------------------------------------------
transmit rdbyte txdata, bytecntr 'get 1st byte
cmp txdata, #0 wz 'check for end of string
if_z jmp transmit_ret 'exit when end of string reached
'ready byte to transmit
or txdata, #$100
shl txdata, #2 ' 2 stop bits
or txdata, #1
mov txbits, #11 ' 11 total bits
mov txcnt, cnt
'----------------------------------------------------------------------------------------------
:bit shr txdata, #1 wc 'output bit on tx pin
muxc outa, txmask
add txcnt, bitticks 'ready next cnt
'----------------------------------------------------------------------------------------------
:wait mov t1, txcnt 'check if bit transmit period done
sub t1, cnt
cmps t1, #0 wc
if_nc jmp #:wait
'----------------------------------------------------------------------------------------------
djnz txbits, #:bit 'another bit to transmit?
'----------------------------------------------------------------------------------------------
add bytecntr, #1 'next byte in string
jmp #transmit
'----------------------------------------------------------------------------------------------
transmit_ret ret
{
######################################## Undefined data ####################################
} ' temp variables
t1 res 1
t2 res 1
t3 res 1
descptr res 1
ipptr res 1
dbmptr res 1
pcentptr res 1
bitticks res 1
bytecntr res 1
rxtxmode res 1
txmask res 1
txbuff res 1
txdata res 1
txbits res 1
txcnt res 1
time res 1
{
######################################### Defined data #####################################
}
LoopTime Long 2_000
line1a Byte "test string 1", 0
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Tom
Comments
Cheers!
Paul Rowntree
That portion of the code is direct from FullDuplexSerial so I don't think that's the problem. Thanks all the same.
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Tom
-Phil
That did it.
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Tom
I believe you are incorrect on CNT always being unsigned.· In my experiments here, CNT is signed running from -max to +max.
Chris
-Phil