UART usage - I cannot see the light in the SDK

[Thomas]

In advance I would like to say I’m sorry for the frustration that this message reflects…Event though I have been using the UART for some time, adding more functionality makes me search documentation for a UART description, and this makes me really frustrated.

I have what I think is a relatively simple need, I want to use UART0 and UART1 on a nRF32840 (both for some RS485 communication).

 

I do not care if it is NRF_DRV, NRFX or APP layer, anything that can be made to work will do!

 

Originally, I thought that selecting between NRF or NRFX was simple; documents suggest that NRF is legacy and I should use the "new" NRFX layer.

So selecting NRFX_UART_ENABLE would be logical and then including nrfx_uart.c driver file.....

But nothing is that simple with this SDK.... there always seems to be a mess of dependencies between configuration macros and files you need to include. and absolutely nothing that documents it (except heavy reading of header files of course ;-). I would love to see. “If you want this layer, tick this in SDK config and include ….”)

Well initial suggestion as above for NRFX just creates a bunch of errors…. so what is the combination needed...

It seems I can choose between using:

1 nrf_drv_uart

2 nrfx_uart

3 nrfx_uarte

4 app_uart

Can anyone suggest settings that will make just one of these options work, it would be highly appreciated and hopefully spare me a lot of testing and experimentation.

What I’m looking for what is a combination of what should be in SDK Config for

NRFX_UARTE section

NRFX_UART section

NRF_DRV (UART_ENABLED) section

APP_UART_ENABLED (+APP_FIFO_ENABLED) section

And any other sections that have dependencies!

I want to be able to call ???_init, send one or more bytes and receive bytes one by one

[Nguyen Hoan Hoang]

Try this library instead. It's a lot easier to use and more performance. 

https://github.com/IOsonata/IOsonata/blob/master/ARM/Nordic/src/uart_nrf5x.cpp

usage example

https://github.com/IOsonata/IOsonata/tree/master/exemples/uart

performance comparaison from this post : https://devzone.nordicsemi.com/f/nordic-q-a/53106/uart-communication-fifo-error/214454#214454

blog post using uart over BLE the easy way.

embeddedsoftdev.blogspot.com/.../bluetooth-le-with-nordic-nrf51-nrf52.html

[Thomas]

Thank you very much for the suggestion.

I have downloaded the library and made a fast try. I run into some rather difficult things that does not seem easily solvable. I am using Keil uVision.

The library looks quite promising but also has a lot of dependencies. It seems to be depending on GCC that was easily fixed by a pragma (Keil or ARM compiler does not allow anonymous structures).

Secondly it uses some features that are later than C99, not exactly sure. But I am stuck with ARM compiler version 5 that does not support it (atomic). ARM compiler 6 has been around for a long time but seems the rest of the nRF SDK is not compatible with that, so I need to stay on version 5.

[Nguyen Hoan Hoang]

I haven't got around playing with uVision.  There are some issue for creating a lib project.  I tried adding files to the project directly and seems to compile,  not sure if it was v5 or v6. The GCC settings is C11/C++11 though.

[Thomas]

Yes, C11/C++11 is only available with ARM Compiler 6. 

Since nRF stuff is only compatible with version 5, the highest compiler feature I have is C99.

So bad luck.

[Nguyen Hoan Hoang]

Why wouldn't the nRF stuff compatible with 6 ?  I'll recheck later what I was able to compile.

[Thomas]

Maybe it is solvable, I just tried another project, quite few error so maybe, There are some static assert things and maybe worse some macro problems that can be tricky.

[Thomas]

Looking into the problems.

I found a bug in uart_nrf5x.cpp code. Line 434 array index is out of bounds. Array has 16 elements 0..15 and the index used is 16 (the count).

(hope it ok i just report it here)