Hi,

In order to test the maximum baudrate the USARTs work, under Linux on a AT91SAM9263, I have prepared the following setup:

1 board + 2 RS485 transceivers (up to 12Mb/s) + cable cross-connecting RS485 transceivers.

2 processes:
process A => Writes 1024 bytes, reads them back and measures time.
process B => Reads 1024 and writes back. Works as a mirror.

I would like to work at 3Mbps but I haven't been able to reach that rate. In fact, after a change the limit above 115200 bps the transmission rate decreases.
I change the bps using stty and double-check it reading the BRGR register.

The use of DMA is activated, which should allow the device to achieve greater baud rates, but it seems unable to do so.

Could anyone please notice whether I am missing something during this tests? Does any one achieve rates above 2Mbps?

Best regards and thanks for your time.