Tuesday, January 21, 2014

MCP79412 Real Time Clock Breakout Board Review

Recently, Jack Christensen, sent me a few goodies, including this really neat and low cost Real Time Clock (RTC) module. A RTC is useful, because it will keep track of the time even when the power is removed from your Arduino. It uses a long life lithium battery.

It comes assembled apart from the header pins which are included and just need soldering. You only really need to solder header pins to the I2C side of the board. Its a nice design, the pin headers holes just the right size so the pins don't fall out when soldering.

The board costs just $10 (on special offer at the time of writing) from Tindie and comes in an anti-static bag with three URLs on it:
  • Arduino Library: http://goo.gl/97rrbJ
  • Blog Post: http://goo.gl/MkBnjR
  • Tindie Store: http://goo.gl/UzAVcZ

I downloaded the library from the URL on the bag fetching the zip file, copying it to my Arduino/libraries folder and renaming it to remove the word "master" from the end of it. I then restarted the Arduino IDE and then run the examples program TimeRTC.

The module is easily connected to an Arduino using four male to female jumper leads.

The connections are:
  • Vcc on the RTC to 5V on the Arduino
  • GND on the RTC to GND on the Arduino
  • SDA on the RTC to SDA on the Arduino
  • SCL on the RTC to SCL on the Arduino

Uploading and running the test program produced the following output in the Serial Monitor.


This module does not use the usual DS1307 chip, but rather the Microchip MCP79412. This can be calibrated and is more accurate than the DS1307. You can read more about it in Jack's blog: http://adventuresinarduinoland.blogspot.co.uk/2012/09/yet-another-real-time-clock.html

My recommendation is that if you need an accurate low cost RTC then you will not go wrong with this excellent device.

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