Trying to modify Phil's Bell 202 object
OldFartRadioman
Posts: 30
I am wanting to change several things
Initially just need to get transmit to work
Change mark tone from 2200 Hz to 1800 Hz; - I think I have that one figured out
Send no start or stop bits, just the 8 data bits per byte
send no initial marking bits - which sould be simple but is not working
I thought I could just remove the " call #send1" in the xmtlp loop but that results in seeing a data burst about every two minutes
Tried replacing with a nop, same result. It acts like I am jumping into neverland. Thanks for any help
Initially just need to get transmit to work
Change mark tone from 2200 Hz to 1800 Hz; - I think I have that one figured out
Send no start or stop bits, just the 8 data bits per byte
send no initial marking bits - which sould be simple but is not working
I thought I could just remove the " call #send1" in the xmtlp loop but that results in seeing a data burst about every two minutes
Tried replacing with a nop, same result. It acts like I am jumping into neverland. Thanks for any help
'=======[Modulator]============================================================
transmitter and dira,xdira 'Configure pins for output.
mov outa,xouta
mov dira,xdira
xmtlp call #getstat 'Are we still transmitting?
and acc,#STSXMT wz
if_z jmp #standingby ' No: Go back to standby.
rdbyte enq,xenqaddr 'Is enqueue index <> deque index?
rdbyte deq,xdeqaddr
cmp enq,deq wz
if_nz jmp #:dodeq ' Yes: There's data to send; go dequeue it.
call #send1
jmp #xmtlp ' Try again.
:dodeq mov acc,xbufaddr 'Point to next byte to send.
add acc,deq
rdbyte data,acc 'Get it.
add deq,#1 'Increment dequeue index.
and deq,#BUFMAX 'Point back to beginning if past end.
wrbyte deq,xdeqaddr 'Write dequeue pointer back to xdeq.
or data,_0x0300 'OR in the stop bit.
shl data,#1 'Shift left to create the start bit.
mov bitcnt,#11 'Bit count to send is 10.
:bitloop shr data,#1 wc 'Shift next bit into carry.
call #sendc
:xnext djnz bitcnt,#:bitloop 'Go back for another bit.
jmp #xmtlp
'-------[Output bit routines]--------------------------------------------------
sendc if_nc jmp #send0 'Send a bit based on carry flag.
send1 mov inc,frq2200 'Send a 1-bit.
call #sendbit
jmp send1_ret
send0 mov inc,frq1200 'Send a 0-bit.
call #sendbit
send0_ret
sendnop_ret
send1_ret
sendc_ret ret
sendbit mov phscnt,#16 'One bit is 16 times through.
:loop add phase,inc 'Increment phase
mov acc,phase 'Copy phase to scratch register.
call #sine
:putfrqa shl acc,outlevel 'Scale it for proper audio level.
add acc,_0x8000_0000 'Add "zero" level.
waitcnt time,delay 'Wait for it. Waaaiiit for it...
mov padc,phsb 'Just to keep receiver ADC in sync.
mov frqa,acc 'Okay, write the level to frqa for DUTY output.
djnz phscnt,#:loop 'Back for another phase piece.
sendbit_ret ret
Comments
Replaced the the call #send1 with waitcnt time,delay which should be a delay of 1/16th the bit period.
Thinking maybe a hub window sync issue?
Something like
MOV TIMER,CNT ADD TIMER,DELAY