Ed Todd wrote: > > A couple of points: > > If you are not using hardware flow control, you have to continuously poll > the RX line for a start bit. If you have other processing to do, poll it > at least once every 0.25 bit widths. > > If you are using hardware flow control, some OS's and packages tend to > leave RTS high, even when the queue is empty. Raise CTS and poll for a > start bit for a while: try about 1 msec. If nothing comes in, drop CTS. > > When you see a start bit, wait till you are between 0.25 and 0.5 of a bit > width in the start bit before starting whatever you are using for a timer. > If you follow the 'rules', you can handle PC data quite easily, since they > send nice, even data. Media that can give irregular timing (radio, IR) has > its own challenges. > Ed Todd I have been working on a project that needs to listen and do other things at the same time. Using a 16c84 at 4MHz and a rtos I am able to listen, send, feed the send routines, etc just by polling. The application note on microchips web site is very usefull. -- Lee McLaren lmclaren@trumpet.com.au Comstra pty. ltd. lmclaren@comstra.com.au 2 Kirksway place phone 03 62244488 Hobart Tasmania fax 03 62244601 Australia 7000 mobil 018 138682 'It was five hours of Boggs's "channelling". After three hours I asked him to summon up the soul of Jimi Hendrix and requested All Along the Watchtower. You know, the guy's been dead twenty years but he still hasn't lost his edge' Mulder