Getting Started with the DS3232 RTC and a brief comparison of some other RTC chips


Having bought a DS3232 some time ago and after getting it up and running (a relatively easy task), I started on the attached information back in March but it fell by the wayside for a while (starting paying work with longer hours on a new multi-billion $ project for one).
Have wrapped up some words and provide the comparison/tutorial herewith along with some PICAXE code to:
  • set and read the time
  • set and initiate interrupts on alarm conditions
  • read and display the temp from the internal temp sensor.

Trust that newcomers and others find this useful.



Senior Member
Yes, I've been thinking a lot about temp sensor and RTC for PICAXE (and AVR).

My requirements are:

* Operation down to <2V to be good with power from 2xAA rechargeables.
* Temp sensor absolute uncalibrated accuracy better than +/-0.5C.
* I2C or SPI (or OneWire, but less good).
* pref PDIL package available as well as SMD, to make prototyping easy.

A good thermistor is still a decent candidate for temp sensor, BTW, though failing that a TMP112.

I didn't find any combined units that met all my requirements, though I have some others sitting in my components box.

For the AVR I have its ability to use a 32768Hz to run an internal RTC is probably fine (entire AVR using ~1uA maintaining the RTC), but for the PICAXE I think I have settled on the MCP79410.