unintended flash erase

[gorazd]

Hi,

we have a nrf51 mounted inside an AC motor housing which we assume is causing an unintended flash erase from time to time (checked with nrfjprog --readcode).

Is this a valid assumption? Are there any solutions for this problem? E.g. shielding the flash chip etc.

[MartinBL]

Hi,

I'm unable to open your files. They seem to lack file extensions. You can edit your question and attach them directly in your post.

The nRF51 has a design flaw related to the SWD and reset pins and is known to unexpectedly reset itself and maybe enter unknown states. This may be caused by noise on the SWD lines generated by for example magnetic fields. The workaround is to attach a 1k pull-down restistor on the SDWCLK pin as shown in the latest reference schematic. Have you done this? Anyway, I'm unsure how this would result in an erased flash, but the cases I have seen related to magnetic fields have also been related to noise on the SWD lines.