RTC battery-backup: Not keeping charge?

Development Boards MicroMod
1

Hi folks,

I’ve been noticing that when using the Artemis Processor + MicroMod Data Logging Carrier Board (MMDLCB), the RTC does not keep its time when unplugged. To test this, I charged the battery for 24 hours and then unplugged power to the MMDLCB for two minutes. Even after this short time, the battery-backup seems to discharge to the point where it’s no long able to maintain the RTC.

I’m curious if anyone has any thoughts on what could be wrong. I did see there was another post about the RP2040 Processor and how its RTC_3V pin is tied directly to 3.3V. I wonder if this could be a related issue.

Cheers,

Adam

08:31:30.651 -> SparkFun RTC Example
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08:31:59.784 -> It is now 12:32:00.53 03/15/21 Day of week: 1 = Monday <- Unplugged power
08:34:01.698 -> SparkFun RTC Example <- Plugged power back
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2

Hi Adam.

I think that’s most likely what’s causing the issue. It looks like by connecting the two pins on the processor board the RTC battery is trying to power the RTC and the rest of the processor board at the same time. Since the battery has such a small capacity, it drains really fast. I’ll let our engineers know and see if they can come up with a fix.

3

Thanks, Chris!

Are you able to clarify whether it’s the circuitry on the Artemis Processor or the MicroMod Data Logging Carrier Board that’s causing the RTC battery to drain?

Cheers,

Adam

4

It looks like a design issue, engineering is aware and there may be a revision later on.

5

Hi

Did manything get modified? Mine also has the same issue.

Bipman

6

There is no separate power pin for RTC module on an Artemis/Apollo3 processor. Not much that can be done about that. Either try using deep sleep, a larger battery or an external RTC module. None of them is the best solution

7

To directly answer your question, no, there have not been any hardware revisions to the Artemis Processor or MicroMod Data Logging Carrier Board. I wouldn’t hold your breath, either!