115200 Baud to 9600 Baud Translator

[ScottC]

Well, interesting. Now I am trying to take in the character at 9600 and resend at 115200. When I do this code below, my results are not what I want!

For example when I send the number 1, I receive an "a", send 2, I get an "f"
3 a "g", ect till I send 6, the sequence jumps to "n", "o".. Really strange.

I don't know if it is a timing issue or not???? Puzzled.

It was mentioned above that I could change the baud rate on the fly, How is that done? Could the issue be I have different baud rates on different pins, seems it should not matter. I'm lost..

ScottC

DEFINE OSC 20 ' 20MHz oscillator
DEFINE HSER_TXSTA 24h
DEFINE HSER_BAUD 115200 '115200 Baud Out
DEFINE HSER_SPBRG 11
DEFINE DEBUGIN_REG PORTB ' 9600,8,N,1 Serial In
DEFINE DEBUGIN_BIT 7
DEFINE DEBUG_BAUD 9600
DEFINE DEBUGIN_MODE 1
B7 VAR BYTE

'**********************************************

TRISA = 0
TRISB = %00000001
TRISC = 0

'********************************* READ SERIAL PORT

loop: While PORTB.7 = 1 'Wait for start bit
Wend

DebugIn [B7] ' B0 = input character
Pause 500

print: HSerout [B7]

GoTo loop ' Forever

[Bruce]

Are you're still using the 22.1184MHz crystal?

DEBUGIN bit timing is calculated for 20MHz with DEFINE OSC 20.

[ScottC]

yes,

I am still using 22.1184 XTAL. I undersatand what you are saying, from what info I gathered, this or 11.something, 1/2 of 22.1184, or an 18.432 xtal is what you want for error free reception. I am still new at this so I'm still in the learnig curve. But it makes sense what you are saying. I am going to try changing the SPBRG later in the program using DEFINE HSER_BAUD 9600, and DEFINE HSER_SPBRG 143 to change the valuse. I compiled it, have not tested yet, I'll get to in a bit see if that works. What do you think?

Scott

[Bruce]

With HSERIN/HSEROUT you can change the data-rate by writing directly to SPBRG.

Here:
    SPBRG = 129 ' 9600 @20MHz
    HSEROUT ["TEST AT 9600",13,10]
    PAUSE 10
    SPBRG = 64 ' 19200 @20MHz
    PAUSE 5000 ' Time to switch terminal program from 9600 to 19200
    HSEROUT ["TEST AT 19200",13,10]
    PAUSE 5000
    GOTO Here

You can't change DEFINEs at run time, so just write to SPBRG directly if you want to change data-rates with HSEROUT/HSERIN.

With DEBUG/DEBUGIN the data-rate & pins used are fixed, you can't change data-rates on the fly, and you'll want your osc frequency as close as possible to whatever you have it DEFINEed as.

[Ingvar]

OK, think about it .... you're running your pic at 22.1184MHz, PBP thinks it's running at 20MHz. You'll actually run 22.1184/20=1.10592 times too fast. You need to lower your baudrate by this factor to get DEBUGIN to run at the correct speed. 9600/1.10592=8681 should do the trick.