help! how can I change baud rate?

spilz · Guest

hello,

I have a stupid problem and I don't find how to resolve it:

I use a 16f876a and I need to change baud rate during the use

I try it

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

How about using a second #use RS232 line? There is also a set_uart_speed() function in my version 3.242 compiler. What compiler version and which PIC are you using?
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spilz · Guest

I am using v4.065

there is only one uart in this pic, and if I use for exemple :

Ttelmah · Guest

The 'point' about a second #use RS232, is you declare it as a second stream, then you can putc/getc, to this stream when you want one rate, and to the other for the second rate. The #use RS232, will _always_ use the value declared in the _last_ definition 'passed' (does not listen to run time tests), unless you use a stream designator. You can have multiple #use RS232 declarations, by branching in a different way (a search here will find references to this).
set_uart_speed, is the easiest way to do this if you only want to change speeds (the second stream is the only way to support things like parity changes as well).
If you want to access the SPBRG register directly, just use the #byte directive. You are accessing bank 1. The BRG, is address 19, in bank 1, not 99. The compiler is smart enough to do this, if you simply tell it to access address 0x99 (it'll automatically bank switch, unless you use the 'ASIS' directive.
So the 'C' way to do what is in your assembler is:

Guest · Posted: Fri Jun 20, 2008 12:54 am

thanks, it works fine

spilz