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Zanduino / MCP7940

Arduino Library to access the MCP7940M, MCP7940N and MCP7940x Real-Time chips
GNU General Public License v3.0
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Battery backup not working if power to micro-controller is cut #45

Closed UnexpectedMaker closed 5 years ago

UnexpectedMaker commented 5 years ago

Or no clear example on how to do this properly.

BTW, thanks for making this library... it seems super thorough :-)

I have the TestBatteryBackup example working, and I can disconnect 3V to the MCP7940N and then reconnect and it keeps time fine... but if I pull power to the microcontroller, and re-connect, time is reset.

I though it was due to the MCP7940.adjust(); Being called in start, but if I change that to look for the powerfail flag and and adjust based on the power restore time and clear the flag, it doesn't work.

Am I missing something here? The entire purpose of a battery backed RTC is to keep time when power to the main device is down, but I can't find any code setup that does this.

Thanks! Seon unexpectedmaker.com

UnexpectedMaker commented 5 years ago

Ok, Ignore this, seems I don't need to do anything... no adjust at all... when the micro restarts after pulling power, the time continues as normal! It was me thinking I needed to check the power flag myself and adjust time that was making it break!

Sorry for the noise... if there was a way to delete the issue I'd delete it ;)

Seon unexpectedmaker.com

SV-Zanshin commented 5 years ago

No problem at all. I'm glad you found the library useful and don't hesitate to ask any questions that you might have.

manaioussema commented 3 years ago

hello guys, In my case, i get the code stuck in "waiting for power" once i remove the VCC pin from 3.3V and get it back. I'm also attaching a CR2032 coin cell to VBAT pin.