Unlock bootloader for j-link/SWD debugging about uf2-samdx1

[dhalbert]

It is not the bootloader that is locked: it is that the NVMCTRL "security bit" appears to be set. However, this is not true: the J-Link is having trouble talking to the chip, and the flash memory appears to locked.

I saw this myself a couple of weeks ago when attempting to use the J-Link with a SAMD51, and was surprised, since it worked well in the past. It might be a J-Link software problem due to a recent update. I will try this again and see if it happens again.

(The bootloader is protected against overwriting (BOOTPROT), but this is not a problem for J-Link access: we debug chips all the time with BOOTPROT enabled.)

[zunkworks]

Ok, thank you for checking/helping.

[zunkworks]

Were you ever able to check to see if you experience the same problem? Just to confirm, what are the minimum needed connections to the J-Link?

[dhalbert]

Sorry, I was having trouble initially, and meant to revisit this, and then forgot.

I just tried connecting to a Metro M4 (SAMD51J19) and it's working fine now. Just today I installed the latest version of the J-Link software, version V7.54d. When I connected the J-Link, it asked to update the firmware on the J-Link, which I did, and it appears to be working fine.

You can download the latest software for J-Link from: https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPack

[dhalbert]

closing this as apparently fixed