FRAMING ERROR Detection method

[prwatE120]

It should be possible to use a timer in conjunction with the UART framing error detection, especially if you look at the data returned by the UART during the framing error.

I have many sucessfull DMX/RDM receiver designs that do not need to resort to using a second external irq.

I think want Eric meant is : "dont just assume that a Framing Error" is a break.

Peter

[PeakPaul]

Thanks Peter for your reply, can you elaborate a bit more on the method of how to do this because once I've detected a FE, I will have lost an undetermined amount of time from the start of the break I assume?

Paul.

[Nigel Worsley]

Originally Posted by PeakPaul

once I've detected a FE, I will have lost an undetermined amount of time from the start of the break

The exact amount of time will be dependent on the design of the UART, but should be fairly consistent. If using a typical 16x baud rate clock the variability would be +/- 0.125uS which is totally insignificant, the delay from the start of the break to the FE would typically be about 38uS - equivalent to the start bit, 8 data bits and the mid point of the stop bit. Some UARTS sample on 3 consecutive clocks in the middle of the bit and do a majority vote, which would add a bit to the delay but still less than 1uS.

Nigel Worsley