Uart on analog pins P0.02,P0.03 NRF52832

RE: Uart on analog pins P0.02,P0.03 NRF52832

MartinBL — Thu, 07 Dec 2017 13:47:21 GMT

Hi,

Are you leaving the RX pin floating or are you connecting it to something? If you leave it floating in the wind the UART module might pick up some noise and generate communication errors. When you use the default P0.06 and P0.08 pins they are both connected to the Segger MCU on your kit.

Here are two similar cases:

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Tue, 05 Dec 2017 23:06:19 GMT

that's interesting :/ i found that it was an issue with the rx pin only i can change the tx pin without problems. After some debugging i found that i was getting APP_UART_COMMUNICATION_ERROR 4 .

RE: Uart on analog pins P0.02,P0.03 NRF52832

Nguyen Hoan Hoang — Tue, 05 Dec 2017 20:06:08 GMT

Just add retarget.c to your project for printf to uart.

RE: Uart on analog pins P0.02,P0.03 NRF52832

endnode — Tue, 05 Dec 2017 19:52:34 GMT

I'm afraid it's only you and your set-up, I have no problem to change UART pins with nRF51 and nRF52 firmwares... sorry;)

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Tue, 05 Dec 2017 19:48:13 GMT

But seriously can someone explain why changing the pins causes a hardfault this is really annoying.

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Tue, 05 Dec 2017 15:29:09 GMT

The NRF_LOG is not enabled in the example of the uart module. I have found the serial example works fine. However i would like support for printf. I guess i'll write my own handler.

RE: Uart on analog pins P0.02,P0.03 NRF52832

Nguyen Hoan Hoang — Tue, 05 Dec 2017 01:01:17 GMT

Watch out for NRF_LOG UART backend (if you are using it). It reconfigures the UART to pins assigned in the sdk_config.h

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 23:11:33 GMT

Just tried the uart example from nRF5_SDK_14.2.0_17b948a on pins 2 ,3 and 23,22 changing only the file components/boards/pca10040.h and it just pulls tx high . can still see the start message on pins 8,6. what's going on ?

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 22:34:20 GMT

In fact it seems that the uart module only works on pins P0.08 and P0.06

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 21:40:35 GMT

Just as a side note i can set the tx pin as an output and pull it high with no issue.

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 21:09:34 GMT

i had to make clean for some reason. But after the changes i'm still getting the same issue on the dev board with nothing else attached except the saleae.

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 21:02:55 GMT

after a make clean i get the same output

RE: Uart on analog pins P0.02,P0.03 NRF52832

endnode — Mon, 04 Dec 2017 20:59:09 GMT

But normally port/pin assignments are managed in board config header file...

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 20:57:20 GMT

It seems to ignore the changed pins and print to the usb serial out anyways. i changed in the board config for pca10040 and in the main.c

RE: Uart on analog pins P0.02,P0.03 NRF52832

endnode — Mon, 04 Dec 2017 20:41:40 GMT

And stock UART example from nRF5 SDK? That should work, right? And what if you just change PIN numbers, nothing else?

RE: Uart on analog pins P0.02,P0.03 NRF52832

endnode — Mon, 04 Dec 2017 20:41:03 GMT

Because that trace from logic looks like there is something blocking the signal, like some parasite capacitance or other passive/active component connected to these ports...

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 20:40:21 GMT

I have tried this on the devkit as well as the custom board i have made.

RE: Uart on analog pins P0.02,P0.03 NRF52832

endnode — Mon, 04 Dec 2017 20:39:29 GMT

And also not only chip part number but also some details about whole board (like is your FW working on Nordic Dev Kit? What are differences in your HW layout and schematics when compared to some reference design?)

RE: Uart on analog pins P0.02,P0.03 NRF52832

mweger — Mon, 04 Dec 2017 20:38:43 GMT

I have scanned my config a few times and don't see those pins used for anything else.

RE: Uart on analog pins P0.02,P0.03 NRF52832

endnode — Mon, 04 Dec 2017 20:30:43 GMT

Are you sure that you don't use these PINs for anything else? If you try to enable them for more HW peripherals the chip will probably hard fault. Also you don't mention which of many Nordic chips you use...