Honored Contributor
Honored ContributorI will look at adding that in my next version. It should not be hard to do.
longshot --- Quote Start --- originally posted by mschmitt@Aug 28 2006, 04:12 AM hi longshot,
thanks for this new uart. i hope it will be part of the sopc ...
one question comes into my mind.
this module has hw cts.
what about hw rts support for rs485 half duplex transmission ?
if you connect a max485 f.e. to implement a differential half duplex connection between nios2 and a multidrop differential bus, mostly the rts is used to switch between receive and transmit. if the uart would automatically switch from receive to transmit as long as there is data to be transmitted and then back to receive then the software would not need to monitor any buffer of fifo structure.
this would make a rs485 connection fast in the point of switching between receive and transmit, the nios would not have to do that (inside the interrupt routine)
the switchover from transmit to receive and vice versa is always a very important point to be monitored in multidrop half duplex application. if you transmit data and do not switch to receive mode fast enough you could miss the start of data if the system on the other side of the multidrop bus that ist trying to comunicate with you is very fast. i have seen this on new fast plc where they switch over from receive to transmit (to acknowledge the receive of your data) with less than a couple of bittime (1-2 bit time space after the your last stopbit before the send the first startbit).
the fifo between nios and the uart even at 115200 bit/sec is not the problem. the main problem ist the switch time between tx and rx.
anyway thanks for this uart.
michael schmitt
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