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I created an implementation of JeeLabs RTClib for this unit. It’s posted on github.

Just to put things in perspective, +-2ppm is 2 seconds in 11.57 days or one minute in 347 days. Or just about one minute per year.
For a simple crystal RTC, this is great. For a highly accurate timepiece it is marginal. If accurate time is your holy grail, then a GPS or radio time piece might be a better choice. In those cases you get tied back to the world time standard and will not suffer drift.

Are there any issues using this with a 3.3V micro? I have integrated this with a logomatic via the SSP1 and it works pretty well 99% of the time but sometimes I fail to clear the alarm flag – when this happens repeated writes don’t make much difference

Does this work with Arduino?
And also, how specifically should I wire it up?

Cool product! This would go great with the LF radio clock receiver IC. Never set the time in your device again!
http://www.sparkfun.com/products/10060

the decription confuses me abit. it has an temperature-compensated crystal oscillator AND crystal? is this a mistake in the description?
also because this rtc does not come with a battery everybody will have to set the rtc to the right time/date themselves. right?

i think they meant to place Sram instead of crystal.
the headline of the datasheet says “Extremely accurate SPI bus RTC with integrated crystal and Sram”

Super lol. I just ordered the other RTC two days ago. FML.

This is ALMOST perfect for a project a friend is working on, but it doesn’t have the ability to output in granularity of 1/100s or 1/1000 of a second.. Does anyone know of an accurate time chip which would be able to output 1/1000s of a second? It doesn’t even have to be absolute time – Just knowing a duration is fine, but I need to be able to read the clock twice, and know accurately how many 1/1000s of a second have elapsed.
Thanks!!

Does it compensate for DST?

Sweet breakout board. If you don’t need the “256 bytes of battery-backed SRAM”, checkout the ChronoDot2.0 using a sister chip DS3231: http://macetech.com/store/index.php?main_page=product_info&products_id=8.
Its bulbdial clock compatible: http://www.sparkfun.com/products/10021
And a bargain at $15, battery included!

Is there any chance the next batch of these could be produced using the DS3234SN part instead of the DS3234S? This product would be much better if it could operate in the industrial (-40°C to +85°C) temperature range.

It would be great if there was a revision of this which broke out the 32kHz pin – since that can feed the async timer of an AVR for sub-second RTC on the AVR.
(I hadn’t realised at all the CLK pin is the SPI clock. Yeah, kinda obvious now I look at it.)

Seriously, $20 and no battery included? Why?
ALL the other RTC’s I’ve purchased from SFE included a battery. What’s different? My fault for not noticing… but really?

Some help, please. I intend to use the square wave output to trigger an interrupt on a uC. The datasheet says that this line needs a pullup resistor. The schematic for the board shows a 10K resistor and 22pf cap to ground from this pin. I presume that the 10k, since it is on the “high” side of the cap, is not an issue in terms of my pullup resistor.
So… a couple of questions from this newbie. The reference diagram on the datasheet does not indicate a need for this circuitry. Why is it there? Second, any suggestions for a pullup? I was thinking in the 4.7K range.
Thanks all.
Ed

Cancel that question. Half asleep this morning. I figured it out.

One more post: I spent a couple of hours getting the interrupt to work this morning. Two pieces of info that may be of use— (1) The output of the square wave pin on the ds3234 cannot be tied directly to the input of an Arduino. A 4.7K resistor seemed to work fine. (2)You may need to build a delay into your code between detecting a square wave and reading the registers to let the update complete.

Perhaps a bit of help to a real new user. I bought the DS3234 and do have it running. I set the clock by entering it into the code supplied on this page. This only gets to clock close not exact. How can this clock be set to the current internet time? As a newcomer to C language coding, how can I reference the clock time in other programs? I need to trigger a camera during a specific time, as I photograph the space shuttle launches and need to listen for the sound of the launch during the time it may take place. I am using PLC’s to do this in the past but want to try an Arduino triggger for the next launch (Images at MarkWidick.com) Thanks in advance.

Any idea how to (easily) calculate duration using this RTC? I can’t track down a function that would let me subtract a start date and time from the retrieved date and time. I want something similar to:
duration = millis() – startTime;
Thanks!

There is something wrong with the newest version of the arduino ide (0022) and this example code. It calls the ReadTimeDate() one time and outputs it to the serial monitor as expected and it never calls it again. I don’t have enough expertise to understand what is going wrong. I suggest someone with more know-how try compiling the example code in 0022 and note the results. I downgraded to 0021 in order to get this working. I don’t know if the problem is a bug in the 0022 IDE or the code provided here. I would be curious to know if anyone gets it working in 0022, I haven’t ruled out that the problem is exclusive to me/my system.

does the library work with the alarm?

Someone can tell me what is going wrong.
I have used the DS1307 Engine for the propeller and now my dates don’t work correctly. It uses impossible dates like september 31 and then jumps to october 2 the next day. ?
Any help is very appreciated !

Is there any way to make this work with a different coin cell battery? Because I don’t have a CR1225…
I have 3x G8-A's
I have 9x 357's
I have 5x CR2032’s

Hello All
I finally got this guy working. Ref http://www.l8ter.com/?p=375
for wiring and use the Example sketch.
Very weird. First the problem seemed to be the jumper wires I was using between my Uno and the breadboard were picking up “noise” – one wire in particular seemd to be most sensitive – the LOW tie down on the SQW pin – when I used a shorter wire it appeared to work ok but after 20 secs or so the output would appear to get corrupted and fix it self agian after another 20secs – I set SPI.setDataMode(SPI_MODE3) and it seemd to stabilze the o/p
Good Luck

Must use 3.3v VCC, instead of 5.0v VCC used in the above Example Sketch, otherwise square wave output doesn’t work.
Must use SPI_MODE3, instead of Mode 1, otherwise one line correct time, followed by one line 00/00….

PacMan reference in image 4!

I had been using a DS1307, but the timekeeping was not as good as I had hoped. The DS1307 can easily drift by a minute a week. The DS3234 has, so far, stayed within 1 second per week. If you are data logging, I highly recommend the DS3234 over the DS1307. Check out openlog as well if you are into data collection. Openlog makes saving data very simple. The DS3234 makes the time that data is saved very accurate.

Hey All —

I got my DS3234 working, in that I can set the time and read the time, however, the battery back up does not appear to be working. I’ve got it hooked up to an arduino uno and when I remove the unos power and let the chip sit for, say, 24 hours the time is no longer correct.

I’ve got a CR1225 battery that reads 2.9 V

Here is how I’ve got it wired:

*gnd –> gnd

*vcc –> 3v

*sqw –> gnd

*clk –> pin13

*miso –> pin12

*mosi –> pin11

*ss –> A0

Any thoughts?

Working fine on mega2560: RTClib.cpp needed <arduino.h> replaced with <Arduino.h>

50 (MISO), 51 (MOSI), 52 (CLK), 53 (SS), GND & SQK grounded, VCC to +5

include <Wire.h>

include <SPI.h>

include <RTClib.h>

include <RTC_DS3234.h>

RTC_DS3234 RTC(53);

void setup(){

SPI.begin();

RTC.begin();

RTC.adjust(DateTime(DATE, TIME));

SPI.setDataMode(SPI_MODE0);

Serial.begin(9600);

}

void loop(){

const int len = 32;
static char buf[len];
DateTime now = RTC.now();
Serial.println(now.toString(buf,len));
delay(1000);

}