I'm attempting a design on a DMX512 receiver. DMX is a protocol used in stage lighting control systems. It is asynchronous serial, 1 start, 8 data, and 2 stop, no parity, 250kbaud. A packet of up to 512 8bit dimmer values is preceded by a break character, specified as between 88uS and 1 second. This design will be using the 17C43 or 44. I have a couple thoughts on detecting the break. I have seen a few posts here on the subject, and I have some questions. If I use the framing error bit to detect the break, how will I know if I have a real framing error? I thought about programming a 12C5xx to just look for a 88uS low, and then issue an 'interrupt' to the 17C43....but this sounds like overkill to me. I did one of these on an 8051, and I looked for a null character with the 9th bit (1st stop bit) a zero. I can't seem to get that concept to work on a PIC. BTW, clock is 32MHZ Thanks for any info out there... Jerry Musselman jam@ameslab.gov Electronics Technician office:(515)294-7906 258 MD Bldg fax : (515)294-0568 Ames Laboratory, ISU ESG / Electronics