Cannot communicate over UART

RE: Cannot communicate over UART

AZI — Mon, 10 Oct 2016 07:05:15 GMT

Thanks! I got direct UART with external MCU(Arduino) working using the default config with HWFC disabled & UART pin 11 for Rx (unidirectional and didn't use TX) and connecting the grounds.

RE: Cannot communicate over UART

RK — Mon, 10 Oct 2016 04:59:00 GMT

well that has nothing to do with the original question at all, which was about using the UART not over USB. The requirement for DTR from the remote end has nothing to do with the nrf51822 MCU either, the requirement for DTR comes from the interface MCU, the Atmel/Segger chip; and that requirement is documented in the devkit user guide.

RE: Cannot communicate over UART

AZI — Fri, 07 Oct 2016 20:06:54 GMT

It seems nrf51822 UART MCU expects a DTR from the remote end(DTE) while connecting to external MCU over USB. Works fine with termite on PC as it uses Virtual COM port/ CDC and software raises DTR in order to wake up the nrf51822 MCU. Arduino doesn't support this with it's USB CDC.

RE: Cannot communicate over UART

RK — Mon, 12 Sep 2016 12:45:47 GMT

perhaps your UART/USB converter doesn't work, or you're using the wrong baud rate, or the wrong flow control. There's really nothing else to suggest, you've connected the pins, you're running the code, if it doesn't work then you need to get a signal analyser on it and see what's going on.

RE: Cannot communicate over UART

Pawel — Mon, 12 Sep 2016 12:36:13 GMT

Thank you for your answer, RK. I tried other pins(P0.12-P0.16), but result is the same - nothing on terminal. Any other clues?

Below I paste my post from deleted topic:

Hello,

Could somebody tell me how to proper use UART pins located on my nRF51DK board?

I connected RX(P0.11), CTS(P0.10), TX(P0.09), RTS(P0.08) and GND to the relevant pins on my USB/UART converter connected to the PC. DK is powered throught USB cable connected to the PC. I tested ble_app_uart example and these are the results:

In terminal I connected to port COM of USB/UART and nothing happens, even after i restarted board. After that i connected to port COM of USB cable connected directly to the DK and program works well.

So, how should I use these UART pins on my board?

RE: Cannot communicate over UART

RK — Mon, 12 Sep 2016 12:00:38 GMT

Pins P0.9 and 0.11 are already used by the onboard segger, you can't connect the same pins to two UARTS, it's not going to work. Choose pins which are NOT used by the onboard segger or anything else and use those.

RE: Cannot communicate over UART

Pawel — Thu, 08 Sep 2016 10:31:10 GMT

No, it is not working with other pins. When i disable HW flow control it is working, but only with usb pluged into devkit, not working through pins connected to USB/UART converter. I tried examples with UART form SDK and it behaves in the same way. So it should not be an error condition and reset. As I mentioned before, the same code runs ok when USB cable is connected to board, but when I try to connect UART pins to the USB/UART converter it is not working.

RE: Cannot communicate over UART

Ole Bauck — Wed, 07 Sep 2016 15:34:24 GMT

Do it work with other pins? Do it work with the onboard chip if you disable HW flow control?

Your code might run into an error condition and reset, see here.