nRF SDK UART peripheral

RE: nRF SDK UART peripheral

Vidar Berg — Mon, 21 Sep 2020 11:30:12 GMT

Hello,

It's ok to use the nrf_drv_uart_* APIs, it will automatically call into the nrfx_uarte.c implementation when DMA support is enabled. Please take a look at the SDK driver documentation here for more details: UART

RE: nRF SDK UART peripheral

JPSvanderWalt — Fri, 18 Sep 2020 16:20:50 GMT

I am still struggling to figure out how to declare and use both UARTs. I see that nrfx_uart/e.c has functions that include the instance. So my guess would be to use this instead of nrf_uart/e.c?

RE: nRF SDK UART peripheral

awneil — Thu, 17 Sep 2020 17:29:54 GMT

"soft" UARTs are a last resort.

As the nRF52840 has 2 UARTs, you wouldn't want to do that unless you need 3 (or more) UARTs ...

I don't know if Nordic have any soft UART example, but there have been forum posts on the topic before...

RE: nRF SDK UART peripheral

JPSvanderWalt — Thu, 17 Sep 2020 17:06:30 GMT

Thank you very much. Yeah, I meant emulating an UART with software.

RE: nRF SDK UART peripheral

awneil — Thu, 17 Sep 2020 16:28:16 GMT

You can't "create" a UART: the UARTs are part of the chip hardware - so the number is fixed (although you can emulate a UART in software - by bit-banging).

The nRF52840 has two UARTs - you can use them both at once. How to configure what pins are used is described in the Product Spec under 'Pin Configuration':

https://infocenter.nordicsemi.com/topic/ps_nrf52840/uart.html?cp=4_0_0_5_32_1#concept_dly_2sw_sr

https://infocenter.nordicsemi.com/topic/ps_nrf52840/uarte.html?cp=4_0_0_5_33_7#concept_wmv_f2m_wr

The nRF52840 also has USB - so you could implement a virtual COM port on the chip's USB:

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.0/usbd_ble_uart_example.html

RE: nRF SDK UART peripheral

JPSvanderWalt — Thu, 17 Sep 2020 16:00:04 GMT

Thank you for clearing that up. I understand that I can select any GPIO to create another UART. Are there any examples to do this or is it documented in the user manual?

RE: nRF SDK UART peripheral

awneil — Thu, 17 Sep 2020 15:36:28 GMT

[quote userid="91698" url="~/f/nordic-q-a/66047/nrf-sdk-uart-peripheral"]Iam seeing that both the virtual comm port and UART on P0.06 and P0.08 is doing the same thing[/quote]

Not sure what you mean by that.

The virtual COM port is what connects the nRF chip's physical UART (on pins P0.06 and P0.08) to the PC - so that you can interact with it using a terminal - so they will necessarily be "doing the same thing" ?

          PC                                           Dev Kit
  +-------------------------------------+         +-------------------------------------+
  |                                     |         |                                     |
  |    ............      ............   |         |   .............      ............   |
  |    :          :----->:          :   |         |   :           :----->:          :   |
  |    : terminal :      : virtual  :   |   USB   |   : interface :      : nRF52840 :   |
  |    :   app    :      : com port :<===============>:   chip    :      :          :   |
  |    :          :<-----:          :   |         |   :           :<-----:          :   |
  |    ............      ............   |         |   .............      ............   |
  |                                     |         |                                     |
  +-------------------------------------+         +-------------------------------------+