Subject:
|
Serial routines for PA7 at 2400 Baud
|
Newsgroups:
|
lugnet.robotics.handyboard
|
Date:
|
Tue, 9 Mar 1999 19:05:26 GMT
|
Original-From:
|
Simon Schulz <Simon.Schulz@hagener-tgz=nomorespam=.de>
|
Viewed:
|
1133 times
|
| |
|
|
Hi,
I read somewhere taht if i want to use pa7 with 2400 baud that i'll have
to modify the LDAB 37 to LDAB 148. Is this the only change ??
If i try to use this, and i send 0b11111111 on the HB, I get 0b11000000
on the Host (if i try 0b00000000 i get 0b10000000).
That looks wrong for me ...
Can someone help me ? Perhaps i do a mistake with compiling (the .asm to
.icb) file ?
I used the as11 for doing so.
Thank you, Simon
Modified Code below:
* pa7_2400.asm
*************************************************************************
* originally written by *
* Fred Martin *
* fredm@media.mit.edu *
* 5 February 1997 *
* changed to output @ 2400 baud *
*************************************************************************
BASE EQU $1000 ; register base
PORTA EQU $1000 ; Port A data register
PACTL EQU $1026 ; Pulse Accumulator Control register
ORG MAIN_START
* sends a byte at 2400 N-8-1 over port A, bit 7
subroutine_pa7_2400:
TBA
SEI
LDX #BASE
BSET PACTL,X $80 ; enable PA7 for output
* send start bit
BSR a7_bit0
* send 8 data bits
BSR a7_send8
* send stop bit
BSR a7_bit1
CLI
RTS
* thanks to Brian Silverman for this recursive bit output trick
a7_send8 BSR a7_send4
a7_send4 BSR a7_send2
a7_send2 BSR a7_send1
a7_send1 LSRA
BCC a7_bit0
a7_bit1 BSET PORTA,X $80
BRA bit_delay
a7_bit0 BCLR PORTA,X $80
* LDAB changed to 4x37 (for 2400 baud)
bit_delay
LDAB #148
bit_loop
DECB ; 2 cycles
BNE bit_loop ; 3 cycles
RTS
|
|
1 Message in This Thread:
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
