RS232/ASCII error checking

[ianbuckley]

I have an application where one of the devices can only talk ASCII. The application will be in a potentially (electrical) noisy environment. I need to know whether the data transmitted is received properly, so if it is not, I can send the information again. I would like more error checking than simply using the parity bit - ideally CRC. This device does not have a communication co-processor, so implementing the CRC via software would use too much of the processor scan time to be acceptable to the application. Does anyone know of a good way to provide error checking for ASCII with a small hardware package?

[Guest Guest]

Ian Most simple ASCII based protocols use a sum check or LRC rather than carrying the overhead needed for a CRC. This is normally easy to implement but even this might be more than you need. You could simply check for a known condition such as the number of characters in a string or a valid common sequence of characters. The sophistication you need will depend on how critical the data is to your application.