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RTC won't output to Serial Monitor
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Re: RTC won't output to Serial Monitor

by adafruit_support_carter on Thu Jul 02, 2020 6:13 pm

Stacking headers should be fine. Let's check soldering. Post photos(s) showing the soldering on the A4/A5 pins for both the Arduino and the shield.

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Re: RTC won't output to Serial Monitor

by gouletd98 on Wed Jul 08, 2020 10:17 am

Sorry for the delayed response, here is a picture of the Solders for the analog pins. Let me know what you think.
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Image (1).jpeg
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Image (2).jpeg
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Image.jpeg
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Re: RTC won't output to Serial Monitor

by adafruit_support_carter on Wed Jul 08, 2020 12:32 pm

Thanks. Maybe a little cold soldered on the shield pads? But hard to tell for sure. Generally looks OK.

Do you have any other I2C devices? Doesn't need to be a shield. Could be a sensor breakout or something.

Do you have a breadboard, jumper wires, and some 5-10k resistors? (this would be for an I2C sanity check)

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Re: RTC won't output to Serial Monitor

by gouletd98 on Wed Jul 08, 2020 1:06 pm

I only have shields, which are not yet soldered to an Arduino.

I do have a breadboard, jumper wires, and 4.7k/10k resistors though. Should I make something with them?

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Re: RTC won't output to Serial Monitor

by adafruit_support_carter on Wed Jul 08, 2020 1:21 pm

Yep, let's try something with the breadboard. Simple idea - create an empty I2C bus and run the scanner sketch again to see if it will run to completion and show the "No I2C devices found" message. I2C requires pullup resistors on SCL/SDA lines though, so we can't just have empty pins. Let's use the 10k's. You'll need two of them. Then, connect A4 to 5V through one 10k resistor. Then, with second resistor, also jumper A5 to 5V. Use the breaboard / jumper wires as needed to create that. Then run the I2C scanner sketch again.

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Re: RTC won't output to Serial Monitor

by gouletd98 on Thu Jul 09, 2020 4:04 pm

Here is the following circuit I tried to configure. I am not sure if this is what you meant. I'm sure you can tell I am quite a newbie to this so feel free to correct anything.

I did not get any output from the I2C scanner. Just "Scanning..."

Note: I did try with the jumper from A4/A5 on both sides of the resistors.
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IMG_0464.JPG
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IMG_0463.JPG
IMG_0463.JPG (817.59 KiB) Viewed 22 times

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Re: RTC won't output to Serial Monitor

by adafruit_support_carter on Thu Jul 09, 2020 5:44 pm

That generally looks OK. But run it without the shield attached. At this point we want to just verify the UNO itself is working as expected.

And, sorry, looks like maybe the breadboard setup wasn't really needed. I just checked the behavior of the I2C scanner sketch on an UNO without anything connected. Even without proper pullups, the sketch will run OK and report "nothing found":
Screenshot from 2020-07-09 14-34-30.png
Screenshot from 2020-07-09 14-34-30.png (21.94 KiB) Viewed 20 times


Keep the breadboard setup in case it might still be useful. But for now, try simply removing everything from the UNO, including the shield, and run the sketch and see if you can get the same output I got above.

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Re: RTC won't output to Serial Monitor

by gouletd98 on Thu Jul 09, 2020 6:44 pm

With just the Uno it runs perfectly fine.

i2cverify.png
i2cverify.png (16.81 KiB) Viewed 20 times


Could something be wrong with just the shield?

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Re: RTC won't output to Serial Monitor

by adafruit_support_carter on Thu Jul 09, 2020 6:52 pm

OK, good to know that at least the basic sanity check works. Thanks for running that.

It might be the shield. What other shields do you have that could be used for testing?

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Re: RTC won't output to Serial Monitor

by gouletd98 on Thu Jul 09, 2020 7:00 pm

I do have a couple more of the exact same shields but I have not soldered any of them together yet (waiting on the stacking headers to come in). So in the short term nothing easily accessible.

Should I try plugging the connections back in first and then if that doesn't work reply if I run into the same issue with another shield?

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Re: RTC won't output to Serial Monitor

by adafruit_support_carter on Thu Jul 09, 2020 7:11 pm

Would you be OK waiting until you get the headers so we could try one of the other shields? The next best step would be to try something other than the current shield on the I2C pins, and it sounds like these other shields are the only thing available.

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Re: RTC won't output to Serial Monitor

by gouletd98 on Thu Jul 09, 2020 7:44 pm

That is fine by me. I will post a reply once I get it all soldered together and on the current Uno. Thank you so much for the help so far!

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Re: RTC won't output to Serial Monitor

by gouletd98 on Sat Jul 11, 2020 4:33 pm

Good Afternoon Carter,

I actually received the stacking headers and soldered together another shield. Same results where it just keeps "scanning..." indefinitely. Should I test it with another Arduino? I do have another one of those that I could also solder together.

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Re: RTC won't output to Serial Monitor

by adafruit_support_carter on Sun Jul 12, 2020 1:07 pm

Looking into this a little further - it may have something to do with the missing IOREF pin on that Sparkfun board, which is used by the shield:
ioref.jpg
ioref.jpg (29.67 KiB) Viewed 9 times


For your situation, you should be able to tie that in by adding a solder jumper here:
https://cdn-learn.adafruit.com/assets/a ... 1473124961
Jumper IOr to 5V (thick red line). Be careful not to short to 3V.
Attachments
vio_jumper.jpg
vio_jumper.jpg (113.2 KiB) Viewed 9 times

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Re: RTC won't output to Serial Monitor

by gouletd98 on Mon Jul 13, 2020 10:28 am

You're amazing! That was it. Now it works on both shields.

RTC_Working.png
RTC_Working.png (23.04 KiB) Viewed 7 times


The only thing is on one of the shields is saying it is 5 minutes earlier than it actually is. Any ideas?

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