On Wed, Dec 17, 2008 at 10:24:13PM +0100, Matthias Fuchs wrote: > Hi, > > some Exar UARTs like the XR16C2850 support a feature > called auto RS485 half-duplex control. In this mode the > RTS line has a special role when using the UART for > RS485 communication. So I haven't maintained the serial driver for a long time, but when I did, I refused to try to implement hardware half-duplex control because there was absolutely no standards in this space. Which RS-232 lines are involved wasn't standardized, and there was often very strange timing restrictions as well. Some devices required there to be a minimum delay of XX milliseconds between when RTS is raised and when DTR is raised. Other devices have a maximum time between when one side raises RTS and the others side raises DTR. So the challenge is designing an interface for half-duplex which is sufficiently general that it will actually work for all/most of the half-dozen people in the world who still care about half-ruplex RS-232 communications. :-) - Ted -- 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
