The DECUSB pin is stuck at 0V. Cannot program IC

[RobHel]

Hello. I can't program the nRF5340 of a couple of boards I recently received. I have it powered via USB (5V), and nRF_VDD is powered up to 1.8V as expected. 

I've probed all the pins of my hardware and compared them against the dev board hardware. The only difference I've noticed is that my DECUSB pin (B6) is 0V, whereas the same pin is 3.3V on the dev board. My hardware just uses a cap to ground equivalent to the dev board. Is there a reason why this pin might be 0V, other than a manufacturing issue? The MCU is unprogrammed and completely erased. 

Thanks,

Rob

[Priyanka]

Hi Rob,

Could you walk me through a few questions?

I can't program the nRF5340 of a couple of boards I recently received.

Are these boards the nRF5340 DKs ? And if so, are you having an issue with all of them?

I've probed all the pins of my hardware and compared them against the dev board hardware.

Do you have a custom board with the nRF5340 SoC ? And you are comparing them against the nRF5340 DKs?

Kind Regards,

Priyanka

[RobHel]

Hello Priyanka,

This is custom hardware I'm testing. The schematic for the nRF5340 is shown in my original post. I am measuring each pin of the nRF5340 on my custom hardware and comparing it to the corresponding pin of the DK. The DECUSB pin of my custom hardware is 0V, whereas for the DK it is 3.3V. 

Thanks,

Rob

[Priyanka]

Hi Rob,

Maybe you could try supplying the power to VDD_H instead of using the USB. And maybe you could also connect the SWDIO, SWDCLK+VDD and GND.

Also, as I asked previously, are you facing an issue with all the boards that you received recently? Or only a few of them? Since your schematic looks fine, it could also be a case of bad soldering.

Kind Regards,

Priyanka