NRF USB fails after cutting SB40 bridge

RE: NRF USB fails after cutting SB40 bridge

Amanda Hsieh — Thu, 24 Oct 2019 06:54:20 GMT

Hi Asaf,

Could J-Link connect to the DK via J2 or J3? Could it read the registers on the DK with J-Link RTT view?

-Amanda H.

RE: NRF USB fails after cutting SB40 bridge

A.P — Tue, 22 Oct 2019 13:47:50 GMT

Hi,
We no longer suspect the SB40 bridge as the cause of our problem, as we were able to recreate this problem in a board where the SB40 was not cut.
We've now come to suspect working with the flash as the probable suspect for our issue, though we don't completely understand what the problem is.

What is throwing us off is that out of several DKs we've used, all failed (in the way mentioned in the original post) after flashing our software and cutting the SB40 bridge, besides one. One DK kept working without issues even though we followed the same exact steps with all DKs.

At any rate, avoiding working with the flash allowed us to work with USB_CDC via J3.

We will post more info as soon as we understand the problem.

Thanks for the help

RE: NRF USB fails after cutting SB40 bridge

Amanda Hsieh — Wed, 16 Oct 2019 11:46:15 GMT

Hi Asaf,

Please try/confirm the following to help us identify the problem:

Did the boards power up with the battery supply?
Could you double-check that the switches are set:

SW6 - DEFAULT

SW9 - VDD

and take out the coin-cell battery if you are powering via USB.

Also, make sure that the USB cable is not a power-only cable but can actually transfer data as well.
Does the device show up in Device Manager on your computer? Please try to connect and disconnect the kit a few times. It might show up with unexpected names. Also, try with J2.
Have you tried a different USB cable? Faulty cables are surprisingly often the problem.
Have you tried using a different computer? If it works on a different computer we know that the kit is not broken and that it is probably a driver issue.
Have you tried to press the IF BOOT/RESET button while power cycling the kit? It should then show up as a Removable Storage Device. Then you can drag-and-drop the J-LINK interface MCU firmware found here (v170724) onto the storage device to reprogram the JLINK firmware.
Have you measured the supply voltage on the kit? It should be somewhere between 2.8V-3.3V. If it isn't, then the hardware is probably broken.
Have you made sure that you are using the latest J-Link driver version? https://www.segger.com/downloads/jlink
Can the PC detect the other USB device?

-Amanda H.

RE: NRF USB fails after cutting SB40 bridge

A.P — Tue, 15 Oct 2019 12:35:07 GMT

Sorry, forgot to add the development environment we use:
We are using the NRF52840 and softdevice S140, PCA10056, SDK version is 15.3.