Programming the nRF52840 via UART

RE: Programming the nRF52840 via UART

Rakhsh — Wed, 23 Sep 2020 21:52:43 GMT

Yes, I had already done that in all cases. I have done full erase and even sector erase, but same result.

RE: Programming the nRF52840 via UART

hmolesworth — Wed, 23 Sep 2020 20:42:31 GMT

Perhaps try an explicit "erase all" first, if not already tried? Maybe the BT840 pre-programmed firmware has some awkward register settings in flash

RE: Programming the nRF52840 via UART

Rakhsh — Wed, 23 Sep 2020 20:34:23 GMT

Thank you for your comment. I don't think that's the issue. As I said, if I program SoftDevice followed by the App, everything works. However, If I program Softdevice followed by "SecureBootloader" and then the App, it fails. If the issue was the Crystal, then in the first case (Softdevice and App) would have failed too.

RE: Programming the nRF52840 via UART

hmolesworth — Wed, 23 Sep 2020 20:30:05 GMT

I don't think the BT840 has a 32kHz low-frequency crystal so maybe that's the issue; a firmware build is required which doesn't rely on that clock source, including an App which uses instead the low-spec RC oscillator instead of that crystal. Search the devzone for plenty of discussions on this topic, with details of workarounds for not using the crystal