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[DPRG] Serial woes 2
Subject: [DPRG] Serial woes 2
From: Ed K.
edk at kinetric.com
Date: Mon Feb 26 08:08:56 CST 2007
You don't show your declaration for cFromUART, but if it's a signed variable
of more than 8 bits, (e.g. 16) it will have a value of 0xFFF1 or some such,
because of sign extension for signed integer assignment.
Declare it as 8 bits, or as unsigned and the "if" should match it OK.
Otherwise use " if ( cFromUART&0xFF == 0xF1 )"
Ed Koffeman
> -----Original Message-----
> From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org] On
> Behalf Of scott at lighthouse21.com
> Sent: Sunday, February 25, 2007 11:21 PM
> To: dprglist at dprg.org
> Subject: [DPRG] Serial woes 2
>
> Hello all,
>
> I'm trying to grab characters from a serial data stream coming into an
> Atmega 88. If I just debug print them to the LCD I can see the value come
> through that I'm looking for but if I try to capture it with an IF the IF
> never runs. Here's the code snippet:
>
> if (!(UCSR0A & (1 << RXC0))) // See if there's a character waiting
> {
> iFoo = ~iFoo; // do nothing if there's no char waiting
> }
> else
> {
> cFromUART = UDR0; // Get the character from the UART
> if (cFromUART == 0xF1) // If its a time code message, catch
> it
> {
> sprintf (sTimeCode,"%cTIME%d",12,cFromUART);
> LCDBug (sTimeCode);
> while (1); // Show it on the LCD for ever and ever
> }
>
> This IF never actually comes through. If I just run the data straight to
> the LCD you can see 0xF1 go by a couple of times.
>
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