UART Troubleshooting Software

[DigiTan]

Does anyone know of a program (preferably for PC) that can troubleshoot μcontroller UART problems. Say for instance, you have a PIC or AVR, the UART connection isn't working and there's no explaination why. I'm mostly interested in buad rate error %, framing error detection and that type of thing. Not so much flow control errors. Are the any good tools for doing this?

 

[DigiTan]

By the way, I'm using something called RealTerm right now, but it's only helpful if the UART is problem-free. Especially when the true baud rate is unknown.

 

[bananasiong]

How about PICkit2 software?

 

[3v0]

I have always used a scope.

 

[blueroomelectronics]

I'll second the PICkit2 software as both the UART tool & Logic analyzer should make troubleshooting UART problems fairly easy. *Debugger is handy too*
Although the PICkit2 is for PICs the UART tool & LA are a handy tool for any micro.

 

[Sceadwian]

Set the transmitter up to send a constant stream of capital letter "U"s this will output a bit clock on your UART pin which you can time using a frequency counter or a scope to determine the exact baud rate very accurately. If you can send/receive individual characters fine but strings are getting garbled it's probably a framing or clock drift issue. Oft times simply adding a second stop bit will help framing errors go away if you don't have a good baud rate match between RX and TX intentionally adding a delay in between each character transmission will make the problem go away but will also seriously limit your throughput. A UART can handle some pretty gross baud rate mismatches on a single byte basis but they compound on strings and at high data rates.

 

[Nigel Goodwin]

A UART can handle some pretty gross baud rate mismatches on a single byte basis but they compound on strings and at high data rates.

It shouldn't do, RS232 syncronises to individual bytes, that's what the start and stop bits are for.

 

[Sceadwian]

With a good hardware UART and a high clock rate sure. With a software UART on either end all such assumptions are out the window, the OP hasn't given us any details other than he has a UART trouble which is more than a little vague, and there is no program or software that can solve that for you.

I'm going to asume a software uart is used on at least one end as anyone that knows how to setup the hardware UART of both a PIC and an AVR should be able to debug it and isn't going to be asking this kind of question with such a vague request as "a program that can troubleshoot UART problems" as such a request doesn't make sense in the first place.

 

[Nigel Goodwin]

With a good hardware UART and a high clock rate sure. With a software UART on either end all such assumptions are out the window, the OP hasn't given us any details other than he has a UART trouble which is more than a little vague, and there is no program or software that can solve that for you.

Doesn't matter if it's a hardware or software UART, it still syncronises every single byte, so long strings make no difference whatsoever. The only time it could make a difference, but it's nothing to do with the UART anyway, is what your program is doing with the data - with a software UART it's got to finish whatever it was doing before the end of the stop bit - but this is simply obvious programming practice.