Fix for Isse #88: check BOD as well as POR when checking for double-c…

[JetForMe]

Fixes #88.

Works for SAMD21, not sure about SAMD51.

[JetForMe]

SAMD51 may have different BOD bits to test.

[JetForMe]

Does anyone review these?

[dhalbert]

@JetForMe What is the behavior you're trying to get by this? Do you want to enter the bootloader on brownout, or only on multiple brownouts?

[dhalbert]

@JetForMe What is the behavior you're trying to get by this? Do you want to enter the bootloader on brownout, or only on multiple brownouts?

OK, I looked at the other issues, and now understand the context. It's good to explain more fully when you submit a bare PR that doesn't reference an issue.

[dhalbert]

This makes sense to me after I looked at the referenced issues. You can submit PR's to https://github.com/adafruit/uf2-samdx1 as well; we try to keep these repos in sync.

[dhalbert]

Take a look at adafruit#111, which waits for 100ms for stable voltage. That was to solve a spurious flash write problem on SAMD51 due to low/erratic voltage.

[JetForMe]

Oh, I may have not properly referenced the issue, but I did mention #88 in the title. I had put the project aside when the pandemic hit (busy getting laid off), but decided to look at it again yesterday which is why this came up again.

[dhalbert]

Thanks, I missed the title reference. I put a "Fixes ..." in the OP so the issue will be linked. I will need to test this on a SAMD51, though I think the behavior may already have gone away due to adafruit#111 (which is not yet in this repo).

need to test on SAMD51

[JetForMe]

adafruit#111 may prevent it, but still seems like it's more correct to check for a double-tap of the actual reset button, not just any reset source.

[dhalbert]

adafruit#111 may prevent it, but still seems like it's more correct to check for a double-tap of the actual reset button, not just any reset source.

I agree, I would still plan to incorporate this.