UART faster than 1Mbps?

[Michael]

I was a bit surprised to see that 1Mbps was the fastest that the UART (and UARTE) supports. Is it really so that it can not be run at 2Mbps (which I would need)?

[hmolesworth]

You can run the UART Tx transmitter at 1, 2, 4 or even nearly 8Mbps (I have done this) but the receiver is limited to 1Mbps due to the usual UART multi-sample-voting algorithm with 16MHz clock and divide-by-16 sampling. I can share code if you want to test that, but it's really only useful for either transmit-only data at (say) 2Mbps or (with a bit of pain) an asymmetrical baud rate half-duplex link with 2Mbps Tx and 1Mbps Rx. It works though.

Edit: I posted the code here custom-uart-baud-rate .. and ah, don't expect Nordic official support to necessarily agree with me (no offence intended) :-)

[ramyasree]

hi hmolesworth 
can you please share the code with me?
i am currently working on nrf52840 uart for a custom board trying to reach above 1mbps, so can you please share the hardware pics/requirments if possible.
.
it would help my work.

[hmolesworth]

Yes, here are a few links; iosonata now has the upgraded calculation included although there is some discussion on which higher baud rates work in a given system. One issue is whether the far end (where the nRF52/3/4 is the near end) can precisely support some of the higher rates; using Loopback mode on the nRF shows whether nRF-to-nRF works at a given baud rate.

technical-question-regarding-uart-baud-rate-generator

uart-sample-code-for-receiving-transmission

uart-transmission-max-bytes

uart_nrfx.cpp

[ramyasree]

thank you hmolesworth