115200 Baud to 9600 Baud Translator

[Bruce]

You get the error because N2400 hasn't been defined.

Declare N2400 as a constant first.

N2400 CON 16780 ' <-- Baud modes shown in manual for serin2/serout2

Now you can use N2400 with serin2 to set the baud mode.

Note: Look at the DEBUG / DEBUGIN commands if you want high-speed serial without a hardware USART, odd value or fast crystal. With DEBUGIN you can easily get 115200bps with a 4MHz crystal. You can't with serin2.

You can use the 16F84A running @20MHz with DEBUGIN receivng at 115200, and serout2 re-sending at 9600, but you'll want a crystal speed > 4MHz for serin2 @ 9600 if you want reliability.

[ScottC]

Bruce,

Thanks for the info, but to run up the rate, what number do I use for 115200?
The manual only shows values up to 9600 baud using 4 mhz xtal. Or is there a way to calculate that number or do you "FOOL" PBP by substituting a different xtal?

Scott

[Bruce]

As shown in the manual, to find the value for a given baud rate, use the equation (1000000/baud)-20. This doesn't work for serin2/serout2 @ 115200 bps.

With DEBUGIN it's simple.

DEFINE DEBUGIN_REG PORTC
DEFINE DEBUGIN_BIT 7
DEFINE DEBUGIN_MODE 0 '1 = Inverted, 0 = true
DEFINE DEBUG_BAUD 115200

Yes. There are ways to trick PBP into working at higher data rates with serin2 & serout2, but then everything else in your program is whacked timing wise since PBP adjusts timing for everything else based on the defined osc speed.

[ScottC]

I have been messing with this for a bit and no luck. I am using a 16F873A with UART. I see a burst of data on my scope, but PC does not see it. I also know that I have to invert the signal due to the nature of HSEROUT.

Is what I have code wise correct?

Any Ideas? I am using a 22.1184MHz Xtal. code is below.
Just using this as a test to see if I can get 115200 baud to work. Then I'll try to concour the above issue posted.


DEFINE OSC 20 ' 20MHz oscillator
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 20h
DEFINE HSER_BAUD 115200
DEFINE HSER_SPBRG 2
TRISA = 0
TRISB = 0
TRISC = 0

PORTB.0 = 1

START:

HSerout ["12345",10]
Pause 1000

GoTo START
End

Thanks,

Scott

[Ceug2005]

try at lower speed
this what i use , not tested uper 9600

define OSC 20
DEFINE HSER_TXSTA 20h ' enable the transmit register
DEFINE HSER_BAUD 2400
.
.
.' +/-
HSEROUT [dec sign0,10,dec tempc0,13]

better to use an MAX 232 to conect at COMx

[Ingvar]

DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_SPBRG 11

[Ingvar]

.... and mode 97 should give 9600 baud with SEROUT2. However, you would probably do yourself a favour by switching to a 20MHz crystal since PBP likes that better, all timings will be correct. 115200 baud works quite well with 20MHz and HSEROUT.

DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_SPBRG 10

.... will give you 115200 with 20MHz.