NRF51822 TWI Master (Software) results in BLE Disconnects

RE: NRF51822 TWI Master (Software) results in BLE Disconnects

Ole Morten — Fri, 07 Mar 2014 11:29:27 GMT

The general recommendation is to make sure the ripple on VDD is less than 100 mV. I'm not sure what kind of effects ripple above this will have on the chip, but it could be that it can affect the stability or startup times of the oscillators, which in turns may ruin the BLE link. When debugging, the 16 MHz clock will be continuously running, and hence may mask such issues.

Anyway, great that you found a solution and posted it! I'll definitely keep it in mind for future cases and questions!

RE: NRF51822 TWI Master (Software) results in BLE Disconnects

Adrian Eggenberger — Fri, 07 Mar 2014 11:26:26 GMT

The behavior is really odd, but the solution is easy. It turned out, that the supply voltage was the problem. There was a lot of noise on it, but it never gets below 2.4V. Adding a capacity to the supply voltage did fix any curious behavior. So the problem is fixed, but it would be interesting, why the noise on the supply may lead to disconnects even when the voltage remains in normal range.

RE: NRF51822 TWI Master (Software) results in BLE Disconnects

Ole Morten — Fri, 07 Mar 2014 11:20:40 GMT

This sounds a little odd, and I can also not quite understand how this happens. The only thing I can think of is a HardFault or similar, but this should be visible when letting the chip run freely in debugger mode, and then stop it when the timeout happens.

If you can supply your complete code project, I'd be happy to take a look on it, and try reproducing the problem. You can either edit your question and add an attachment, or post a regular support case with it.