NRF52840 Problems with Pin Configuration and HX711 example

[Nici W.]

Hello,

I tried to implement the HX711 example from Vidar mentioned here (https://devzone.nordicsemi.com/f/nordic-q-a/34112/best-approach-to-interface-hx711-with-nordic-nrf52832) on my NRF52840 DK. Everything works fine if I use Pin 28 for PD_SCK and Pin 29 for DOUTa. Some other Pin Pairs like 31 and 25 are working too. But there are a lot of Pins which don't seem to work (e.g. 25 and 23) without a reason. Does anyone has an explanation for this?

I tried to use this one on my nrf52840 Dongle which didn't work at all.(or I didn't found the pins yet which work). Does anyone can help with this?

FYI: The App is based on the blue_blinky example.

Regards and thanks

Nicolas

[Simonr]

Hi Nicolas

Are you sure these other pins aren't used for something else in your application, or does the HX711 require either of the pins to be an analog input perhaps?  You can see what pins are analog pins here in the nRF52840 pin assignments: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fpin.html 

You should also check the sample project to see if it uses any of the other pins as well. Here you can check out the hardware drawings of the Dongle to see what pins are available. Please note that soldering pin headers might be necessary. You should also check out our Dongle Programming tutorial to see what changes are necessary in the project to make it work on an nRF52840 Dongle.

Best regards,

Simon