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Failed RTC chip
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Failed RTC chip

by Spiney on Mon Dec 31, 2012 12:53 pm

Hi,
I had my logger shield working some months ago but now I can't get time printed. The shield is mounted on your Proto Screwshield and there are Relativity Humidity and pressure sensors connected to A4 and A5. These have been working with your LCD shield and returning proper figures. When I ask for time I get nonsense.
So I returned to the code provided for testing the RTC provided in your Logger information, and loaded that (no code for the other sensors). Same result. See attachment.
I have tried removing the battery. RTC.adjust(DateTime(__DATE__, __TIME__)); is included.
Is there some way of establishing whether the clock chip is working please?
Attachments
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Re: Failed RTC chip

by adafruit_support_bill on Mon Dec 31, 2012 2:15 pm

Is there some way of establishing whether the clock chip is working please?

The test sketch output is saying "RTC is NOT Running".
Make sure you are getting a good voltage on the battery. These last a long time in normal use, but will drain very quickly if they are short-circuited somehow.
If it doesn't work with a fresh battery, post photos of the front & back of the shield. You may have a cold-joint somewhere that has deteriorated over time.

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Re: Failed RTC chip

by Spiney on Sun Apr 14, 2013 5:50 pm

I have re-soldered all the joints. I have replaced the ds1307. I have re-downloaded your RTC library.
I have loaded the examples from the library and run "softrtc" which works and "ds1307" which does not, giving the same result as I posted before. If softrtc works, surely the RTC is working, despite the "Not Working" remark under ds1307? I have tried to attach photos as requested. but having copied the file "paste" is greyed out on this form.
I will look for instructions tomorrow; time for bed!
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Re: Failed RTC chip

by adafruit_support_bill on Mon Apr 15, 2013 6:31 am

SoftRTC uses software to emulate the RTC. It does not talk to the DS1307 chip.
To post photos, use the "upload attachment" tab under the message editing window. If the images are large, resize them to about 800x600 before uploading.

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Re: Failed RTC chip

by Spiney on Thu Apr 18, 2013 4:35 am

I have a scope. I would like to try some diagnosis. Suggestions for what and where to look would be helpful if you have some.
Underside of the board looks a bit scruffy as a result of re-soldering and flux residue cleaning, but I don't think there any dry joints or shorts.
Attachments
RTC2 003.JPG
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RTC2 001.JPG
RTC2 001.JPG (157.06 KiB) Viewed 1127 times
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Re: Failed RTC chip

by adafruit_support_bill on Thu Apr 18, 2013 6:57 am

You can check the legs of the crystal to see if it is oscillating. You can also look at pins 5 (SDA) and 6 (SCL) on the DS1307 chip to verify that there is i2c communication activity.

Also make sure that you have 3v between ground and the battery holder with no power connected to the board. Make sure there is a bump of solder on the pad under the battery for good contact.

Image

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Re: Failed RTC chip

by Spiney on Fri Apr 19, 2013 5:42 am

Thank you.
3v checks out OK. There is 3V on pin pin 3 of DS1307. There is no oscillation on the Xtal pins, just 0 & 2.2V DC. Pins 5 & 6 of DS1307 show 5V when USB is connected. This is the same with old or new DS1307.
Guess I need another Xtal.
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Re: Failed RTC chip

by Spiney on Mon Apr 22, 2013 4:33 pm

Sadly the new xtal has not solved the problem. I wonder why Adafruit only now offers these shields assembled? Is there a capacitance/Inductance problem with the board which might prevent oscillation? I note that there is advice to keep connections away from the interface between DS 1307 and the xtal. Having now replaced both ds1307 and the xtal I am stumped!
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Re: Failed RTC chip

by adafruit_support_bill on Mon Apr 22, 2013 6:39 pm

Other than a bad lot of crystals a couple years ago, we haven't had many crystal problems with these. The most common issue with these boards was soldering the surface-mount SD card holders.

Not sure why a working crystal would suddenly stop oscillating. The few bad ones we've seen just never worked at all.

One more thing to try: Remove the protoshield with the other sensors and see if you can get it to work with just the logger and the Arduino.

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Re: Failed RTC chip

by Spiney on Tue Apr 23, 2013 7:44 am

Thank you.
In fact I have been doing these recent checks with the shield connected to a second Arduino Uno with nothing else connected.
I have just tried the shield on its own, with power from the arduino supplied on jump leads. Still no oscillation.

I bought 2 xtals from Farnell, delivered yesterday. I have just tried the 2nd one. Still no oscillation.

I have also wired up the DS1307 and the xtal on a bread-board, without pull-up resistors on the SCL & SDA. 5 Volt from the Arduino, 3 Volts from a bench supply. No oscillation. Not sure what that tells me! If stray capacitance is important, maybe that would not work. If something on the shield is blowing the DS1307 then it will already be dead. Likewise the xtals.

It is so long ago now, that I wonder if I really did have time and date shown. The 3 records on the SD card,taken last year, do not show recognizable date and time, but maybe I did see it on the serial monitor.

I remain stumped! Might be worth wiring up an oscillator with an op amp to check the xtals away from the DS1307, but I would need to find a circuit.
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Re: Failed RTC chip

by adafruit_support_rick on Tue Apr 23, 2013 8:53 am

I have seen that behavior when running my shield without a battery installed. Same symptom - time is 165:165:85. I had no luck reproducing it just now, but I saw it as recently as a few days ago. No idea how a missing battery can cause this. It just is.

Have you tried replacing your battery?

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Re: Failed RTC chip

by Spiney on Tue Apr 23, 2013 2:03 pm

Yes, the battery has been replaced. In fact, initially, solder from the earth-side of the battery housing shorted the battery. After I corrected this, and ensured a good blob for the negative connection, I had to replace the battery.
But measuring the voltage on pin 3 of the ds1307 always shows 3 volts.
There has to be a reason why 165/165/85 appears. It should assist in diagnosis? But I suppose this results from the Arduino receiving no legitimate I2C.
I am going to try to build a simple cct to test whether the xtals are working. If they do ackle I will try replacing the ds1307 again.
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Re: Failed RTC chip

by adafruit_support_rick on Tue Apr 23, 2013 2:15 pm

I don't think it's a problem with your specific xtal or DS1307. Like I said - it's something I've seen intermittently, and it appears to be related to resetting the DS1307. I don't know if it's a shield design issue, or a SW issue, or a DS1307 HW bug.

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Re: Failed RTC chip

by Spiney on Tue Apr 23, 2013 4:35 pm

That is interesting but I don't know how to proceed. In my case the fault is not intermittent.
I have checked the reset button for proper operation ( I wondered if it might be faulty). What does it reset anyway?
One difficulty is not having a full circuit diagram of the shield.
If there is nothing wrong with either the DS1307 or one of the 3 xtals, one might have expected the circuit on the breadboard to work; it did not. (At least with one of the ds1307s and 2 xtals.)

It might be a good idea to try the shield with a completely different program - but it would still be using the same RTC library I suppose.

If I can make the xtals work with a simple circuit, that would remove one of the unknowns. If I could then make a Ds1307 oscillate off the board that would prove the chip. Then, if that pair would not work on the shield it would indicate a shield or software problem.
I shall soldier on. Maybe it would be less frustrating to buy a new pre-assembled RTC shield!
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Re: Failed RTC chip

by adafruit_support_rick on Tue Apr 23, 2013 5:01 pm

I'm not sure what to tell you. If I could get the darned thing to happen again here, maybe I could figure it out.

But you've swapped out all the hardware. I guess all I can suggest is to try messing with the software.

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