I just noticed a nice feature of SAM C2x microcontrollers from Atmel. It is the RS485 support, i.e. one pin (TE) goes high when the UART is transmitting and goes immediately low when the last byte was really shifted out, including stop bits.
There is an additional feature that Atmel named "guard time".
" For RS485 mode, the guard time is programmable from 0-7 bit times and defines the time that the transmit enable pin (TE) remains high after the last stop bit is transmitted and there is no remaining data to be transmitted. "
When the guard time could be useful? I think it's better to disable the transmitter as soon as possible to avoid corrupting the next message from another node on the bus.
Maybe it is desirable another *different* feature, a guard time *before* starting the transmission of a packet. This would give some time to the node that has just finished the transmission that needs to disable its transmitter (...and doesn't have the hardware control of TE pin).