Transmitter failure on the nRF51 ?

RE: Transmitter failure on the nRF51 ?

ovrebekk — Fri, 27 Jan 2017 13:38:13 GMT

If the 16MHz crystal is off it will probably manifest itself in a different way. Please let me know what you discover when measuring it.

RE: Transmitter failure on the nRF51 ?

Roger Clark — Wed, 25 Jan 2017 08:56:48 GMT

I have an app timer running every 5 seconds which reads data from a BMP280, it appears to be working OK, as I can log data to UART and it looks like it is logging every 5 seconds.

Actually I'll attach my scope to the 16Mhz crystal and see if its running and what frequency it seems to be oscillating at.

On a slighly related note, I recall having issues with a batch of boards where they had installed a 32.000khz crystal instead of a 32.768 khz, and this seemed to cause major problems, not just incorrect time keeping.

But I'm not getting the same sort of problems on this board as I did with the 32khz crystal

RE: Transmitter failure on the nRF51 ?

ovrebekk — Wed, 25 Jan 2017 08:08:16 GMT

If everything works except the RF it is often a crystal issue. The radio will not work without an accurate 16MHz clock source, but all the other parts of the system will.

RE: Transmitter failure on the nRF51 ?

Roger Clark — Tue, 24 Jan 2017 23:04:38 GMT

I probably won't put it in the bin. Just in the stack of boards that don't work any more (mainly not nRF51's)

If I get chance I'll try to check the continuity, but I now have 200 machine made boards, which are just the same, so I will try putting on of those in the same position and see if that fails as well.

RE: Transmitter failure on the nRF51 ?

Michael Antwih — Tue, 24 Jan 2017 22:27:15 GMT

Do a continuity check first within your RF path. First make sure you can go from series component to series component and then check all shunts to ground to make sure there aren't any failed components. Are you able to share an image of your RF section? Or you can just place it in the bin but it would be nice to know the failure so the next board up doesn't encounter the same issue.

RE: Transmitter failure on the nRF51 ?

Roger Clark — Tue, 24 Jan 2017 22:19:47 GMT

Thanks Michael

I've checked the board with a usb microscope, and I can't see any dry joints or shorts.

IMHO a short is unlikely as the board initially worked, but when I put it in its plastic enclosure and left it outside (it measures temperature and pressure and other environmental factors), for a few days, I noticed it had stopped transmitting.

Its likely it got reasonably hot in the sun, perhaps 60 or 70 deg, but AFIK that's with the operating spec, and also I would expect it to recover.

The strange thing is that its only the RF that's failed, the rest of the MCU and all the peripherals are still working fine.

I didn't solder the board myself, it was made by a design house in China, and seems quite well soldered (for hand soldering with an iron)

I may run my reflow air tool over it and see if that helps, otherwise I think its going in the bin ;-)

RE: Transmitter failure on the nRF51 ?

Michael Antwih — Sun, 22 Jan 2017 11:48:33 GMT

If your antenna is disconnected from your chip via dry solder, open circuit or component failure; your system will no longer be able to emit rf at 2.4ghz.

Have you probed the circuit to see if you have any open connections or shorts?

When you designed your system did you account for the environment when choosing your components? The failure might be due to component ratings.

Anything that disconnects the chip from the antenna will be seen in the transmission and reception performance. Your device might still be transmitting because could be on a different frequency now since the 2.4ghz radiating element is not in the path.