115200 Baud to 9600 Baud Translator

[ScottC]

Has anyone done a translation table for serial commands? What I want to do is receive data in at 115200 and send out a different string at 9600. maybe 8 to 10 different commands. Is it Possible?

Seems it is. I use Pic Basic Pro. I have done serial in, and serial out only, but never both at the same time, yet alone at different baud rates. I am still kinda new at this, and only delt with PIC16F84. If anyone can recommend a PIC, that would be great too!

From what I can gather so far, looks like I'll use a 16F873 and a 22.1184 XTAL.

Any ideas on how to go about this?

Thanks,

ScottC

[mister_e]

depending of all your requirement, you can also whatever PIC with a internal USART like pic16f628, pic16F870 or elses.

Use a 20MHZ will be enough to have a great 115200 baud reception.

The only thing you'll have to do is to store every data receive in diferent variable or an array. once it's don send all of them serial. You'll be able to change the internal USART baudrate on the spot by changing only the SPBRG register.

[ScottC]

Steve,

Thanks for the info. I will try just that. It will be a few days as I need to order some PICs.

I have never worked with a UART before so that part should be interesting.

Scott

[ScottC]

I don't understand why I am getting errors on this. Is my array set up right?

If I replace BAUDIN with N2400 on SERIN2 line, I only get bad expresion during the compile
Why?
If I can get this to run at 9600, I would like to increase the input to 115200. What should I put in for the OSC? 20MHZ, and run a 22.1184MHZ xtal?

Would like to use a 16F84A or 16F873A with UART
Any Ideas?

Thanks,

ScottC

DEFINE OSC 4 ' 20MHz oscillator
RSDATA VAR BYTE[7] ' Data input array
BAUDIN CON 16468 ' 115200,8,N,1 Serial In
BAUDOUT CON 16468 ' 9600,8,N,1 for Serial Out
TX VAR PORTA.0 ' Pin for TX
RX VAR PORTA.1 ' Pin for RX
'********************************************

TRISA = %01000010

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

LOOP:

SerIn2 RX,BAUDIN,[WAITSTR RSDATA\7] 'serial data in on PortA.1

[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.