UICR values not stable

RE: UICR values not stable

Jared — Fri, 12 Nov 2021 11:30:49 GMT

Hi,

[quote user="Andrea Lombardo"]I was thinking it could be related to battery power or GPRS RF field power.[/quote]

It's plausible that an unstable supply would give wrong readings, but in that case the power supply supervisor should do a brownout reset. Could you also check the reset register when your receive the device?

regards

Jared

RE: UICR values not stable

Andrea Lombardo — Fri, 12 Nov 2021 10:25:25 GMT

I have asked the customer to return the device. Hopefully I should have it here within two weeks. In the meantime I have upgraded the firmware to another device that was switching between two configurations. The modification was in the reading routine of the UICR register. I read them for 1 seconds (do not know how many times) and I return the value only if every reading is coherent. So far I did not get any wrong reporting, but it is early to say (usually they report the wrong number every 2 days). I was thinking it could be related to battery power or GPRS RF field power.

I will update the ticket with some news as soon as I get the device or I have more robust findings from the one that have been reprogrammed.

RE: UICR values not stable

Jared — Fri, 12 Nov 2021 10:17:41 GMT

Hi,

Ok, so you haven't checked the register directly, you've only by checked via the cloud? The UICR register bits can only be flipped once before you have to erase the flash. If it switches between 0 to 1 without an erase, then it means that it's probably something else that is the problem such as your application. Could you check the registers directly on a sample by using the SWD interface and reading out the UICR?

regards

Jared

RE: UICR values not stable

Andrea Lombardo — Fri, 12 Nov 2021 06:50:56 GMT

Hi,

UICR are written only during production phase. Specifically, customer[8] and customer[9] are written only after the reception of a special command from the cloud to give a name to the device.

Yes, there is a bootloader on the board, but we have not released any OTA yet, so the device in the field is running with the same fmw version it was produced.

See the extract from the database in our cloud system

as you can see, the device presents itself as ATJGDNZ that is its proper name, but it happens that it reports AJTWDNZ.

It looks that one bit has not been programmed to 0 "well enough" as the difference between the two character is just one bit.

I never rule out firmware bugs, but if the fmw should zero that bit, this would be forever and it will not show up high again after few seconds.

Any thoughts?

Thanks

Andrea

RE: UICR values not stable

smackenzie — Fri, 12 Nov 2021 00:25:31 GMT

I have observed similar things when the ground line for the SWJ connection was not properly contacting. Perhaps check your programmer.

RE: UICR values not stable

Jared — Thu, 11 Nov 2021 14:39:46 GMT

Hi,

Does any of the other registers in the UICR change or is it just the CUSTOMER registers? Do you write to the UICR any other place in your application? Are you using a bootloader?

regards

Jared

RE: UICR values not stable

Andrea Lombardo — Thu, 11 Nov 2021 12:09:26 GMT

Yes, exactly. This is what looks that happens.

Thanks

Andrea

RE: UICR values not stable

Jared — Thu, 11 Nov 2021 12:04:59 GMT

Hi,

The code looks ok.

[quote user=""]

What worries us more is what we have recently discovered.

We have a couple of devices that present themselves with different names at different times.

[/quote]

Do you mean that the UICR register change in the field after you have verified that the correct value is writing during production?

regards

Jared