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I have a doubt I hope somebody can help me

I am thinking to add to my project using Arduino Mega 5V a DS3232 real time clock. I can see on data sheet some information about the MAX voltage for SCL SDA. I know I can connect directly to 5V the DS3231, But If I disconnect the VCC to work only with 3V battery cr2032 ...

My question is:

Will the I2C communication work? Because Arduino will use 5V and DS3231 3V. If not, why they add option to use battery, for MCU 3v3 ?

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This is my understanding of the question:

I know I can power DS3231 with +5V. But If I disconnect the Vcc to work only with 3V battery (CR2032), will I be able to communicate with the RTC?

If the Vcc is powered down and the RTC is powered only from the backup battery, the microcontroller (MCU) will not be able to communicate with it through I2C. I'm guessing that the MCU and RTC are powered from the same rail. So, when Vcc is powered down, the MCU itself is powered down, and it wouldn't be communicating.

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  • \$\begingroup\$ why the battery?? If I can’t use? When I will replace the battery of project the RTM will erase the time/date? \$\endgroup\$ – asterix May 10 '19 at 21:11
  • \$\begingroup\$ Normally Cap backup allows 1 minute replacement time \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 10 '19 at 21:34
  • \$\begingroup\$ I watched a youtube video how to use DS3231 module. I could see the CR2032 battery option is only to remember date configured in first use of DS3231. After unplugged the VCC power of your system, the date will be stored and running for a long time... \$\endgroup\$ – asterix May 11 '19 at 0:54
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The following link shows that the DS3232 works with both 3V and 5V so the communications will work OK. It is a very good link to use to learn to use the part. https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/arduino-usage

The part is a Real Time Clock, and the battery provides it with power when it is not powered up in a circuit.

I have read the battery may last up to 2 years.

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  • \$\begingroup\$ Thanks....I watched a youtube video how to use DS3231 module. I could see the CR2032 battery option is only to remember date configured in first use of DS3231. After unplugged the VCC power of your system, the date will be stored and running for a long time... \$\endgroup\$ – asterix May 11 '19 at 0:54

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