Blinky Example on nRF52840 Custom Board

[EE Michael]

Hi Yall,

I designed a custom board with SoC nRF52840, and developing software with nRF Connect extension in Visual Studio Code. 

I followed the dev academy instructions on how to create a custom board, setup device tree, and flash the Blinky example successfully.

My issue is that the toggle function behavior differs based on the pin assignment. For example, if I revise my led0 assignment to P0.8, P0.11, or P0.24, then I get a different behaviors. To be transparent, all three pins are connected to different load/circuitry:

DT configured led0 at P0.8, the circuit is a 22Ohm series resistor into a CS slave pin. The output is a square waveform, but the two states are 0V and 700mV.

DT configured led0 at P0.11, the circuit is a 22Ohm series resistor into another CS slave pin. The output is a square waveform with the expected two states at 0V and VDD (3.3V).

DT configured led0 at P0.24, the circuit is a 3.3k series resistor into cathode of an LED to VDD. The output waveform is 2VDC.

Thanks,

EEM

[Hung Bui]

Hi EEM, 

Please check the device tree configuration. I suspect that the pins may be used in other peripheral causing the pins to behave differently. 

Please try to disconnect the pins from the series resistor and measure again to double check if the output match 3.3V. You can also test by connecting the button pins on the DK to the custom board and check if the voltage level is correct. 

Please attach your device tree so we can take a look. 

[EE Michael]

Hi Hung,

I appreciate your feedback. I included my customBoard.dts and started to delete a few 'properties' or disable certain things in attempt to resolve the issue.

I can disconnect the circuit elements, and retest the problematic pins. I'll report back on your recommended hardware troubleshooting this evening.

I did go back and verify the layout with one of my spare boards via continuity. Additionally, I also tested the LED to make sure it was connected correctly cathode pointing to P0.24 and verified component functionality using DMM diode test function. I'm hoping it is just DT conflict, but there may be an unintended connection.

Much appreciated,

EEM

customBoard.dts2605.prj.conf