Arduino Giga RTC doesn't remember the time

Official Hardware Mega GIGA R1 WiFi
1

Hi All

I've got a fleet of gigas, and we're working on the RTC capability. Ours are powered by a 3v CR2032 on our PCBs, and the RTC doesn't keep the time (i.e. resets back to 00:00:00) if we leave it unplugged for more than a couple of minutes. I've observed this behaviour on a couple of them now.

So my questions are? What voltage should I power the RTC at (googling shows me only that the pin is called VRTC) and when I check the specs, I see no reference for what this should be. My multimeter is showing 3.24v between VRTC and GND.

Thanks for your help - having this onboard is important to us, so I do need to get it working reliably.

2

There are many possible problems, post an annotated schematic showing exactly how this is wired.

That would be about right with a fresh battery. Also try another RTC chip as it is possible it got zapped in handling.

3

Looking at the processor spec: Vbat should be between 1.2 to 3.6 Vdc

from STM32H747xI/G:

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4

Try and use 3.3V from say another Arduino board and run the RTC sketch at https://docs.arduino.cc/tutorials/giga-r1-wifi/cheat-sheet/. Make the necessary change as shown in the screenshot (screenshot from my test) below to reflect the current time and date.

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5

Hi,

Did you get anywhere with this? We have the exact same issue here.

Andy

6

This thread seems surprisingly dead. It tests out OK for a few seconds/minutes, and then nothing. It resets. We've tried this on 3 giga R1s and have exactly the same behaviour. For a schematic, it's a simple as +3.3v from the battery to the correct pin, -v (from the battery) to the GND pin.

7

Hey

It seems to work for me. “Schematic” is clear. Please share your sketch.

8

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