ChronoDot 32K external device clock
Moderators: adafruit_support_bill, adafruit

ChronoDot 32K external device clock

by fedez on Mon Sep 03, 2012 7:08 pm


I would like to use the 32 kHz clock signal.
The documentation states the following:

The 32K pin is open-drain (needs a pullup resistor) and outputs a 32768 Hz clock signal. This can be enabled using the EN32kHz bit in the Status register (address 0x0F). This pin could be used as an accurate oscillator reference for some external device.

If I am correct I need the following code? Right?
Code: Select all | TOGGLE FULL SIZE
void setup()
  // clear /EOSC bit
  // Sometimes necessary to ensure that the clock
  // keeps running on just battery power. Once set,
  // it shouldn't need to be reset but it's a good
  // idea to make sure.
  Wire.beginTransmission(0x68); // address DS3231
  Wire.send(0x0E); // select register
  Wire.send(0b00011100); // write register bitmap, bit 7 is /EOSC

  Wire.beginTransmission(0x68); // address DS3231
  Wire.send(0x0F); // select register
  Wire.send(0b00001000); // write register bitmap, bit 3 is EN32kHz

I am thinking on using a 10K resistor connected as in the attached image.
pullup.png (16.14 KiB) Viewed 1094 times

Is this correct?

Thanks all for any help!
Posts: 5
Joined: Wed Aug 22, 2012 7:23 pm

Re: ChronoDot 32K external device clock

by adafruit_support_bill on Tue Sep 04, 2012 6:14 am

That looks about right, but I haven't tried it myself. Macetech (the designers of the Chronodot) come by these forums fairly regularly. But you might get a quicker answer if you contact them directly:

Posts: 37639
Joined: Sat Feb 07, 2009 10:11 am

Re: ChronoDot 32K external device clock

by fedez on Wed Sep 05, 2012 12:36 pm

I will try my setup once my chronodot arrieves!
I'll let you know if it worked.

Posts: 5
Joined: Wed Aug 22, 2012 7:23 pm