On Mon 18 Feb 2008 13:36, Robin Getz pondered: > It is quite common on many industrial serial devices which do not > support either software or hardware flow control to require a > Inter-Character delay longer than than the standard one, one and a > half, or two stop bits. > > A device where this long inter character delay is required are devices > like Point of Sale terminals, and devices that are talking to Modbus > (Honeywell SI-FTA implements a check on the inter-character gap). > > Some hardware manufactures have seen this need, and added it to their > UART controllers - Atmel's AT32AP7000 has added this and called it a > "Timeguard" (Don't ask me why). The "timeguard delay" is controlled > between 0 and 255 Bit Periods. > > http://www.atmel.com/dyn/resources/prod_documents/doc32003.pdf > > I think I have seen similar things for some ARM devices, and other > embedded architectures. Today, we have done similar things in the driver > (on hardware that doesn't support it natively). > > I'm not sure that bit periods are the best way to measure things, or > milliseconds. I guess it really doesn't matter, as long as everyone does > it the same way - which brings me to my next question: > > Does anyone have a good idea of a standard way to expose this to > userspace? > - grabbing 8 bits in the termios_p c_oflag isn't going to fit > - adding a new field in the termios structure seems like overkill > - adding backdoor ioctls for serial drivers seems like a bad idea. > > Thoughts? ping. Comments appreciated. -Robin - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
