RTC Pi not detected on i2C grid

Hi,

I recently purchased the RTC Pi from Core Electronics: RTC Pi - Raspberry Pi Realtime Clock module

Current set up:

  1. Raspberry Pi 4 B+
  2. RTC Hat connected onto RTC directly ontop of GPIO pins with the CR battery placed
  3. I confirmed my CR2032 battery isn’t dead as it’s new and measured a voltage of 3.22V.

I have ensured the CR battery is connected the entire time when on the PI 4. I have enabled i2C In the Pi configuration settings and sudo rebooted.

I am not receiving any devices on the i2C grid when using sudo i2cdetect -y 1

Your help would be much appreciated.

Edit: I have already installed IC2 Tools: sudo apt-get install i2c-tools

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Hi Samuil,

That link is to a different website, but I presume it’s still a DS1307 RTC?

Adafruit have a really good tutorial on this, whichever model of RTC you’re using:

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sudo apt-get install python-smbus i2c-tools
i would code the above and reboot the rpi then run detect again
depending on which way you go about things…

most common issue is reversed scl/sca lines …or data lines check these are correctly matching…
when building home brew units…

also this is the device you gave a link to…is setup page

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Hi Brian,

Thanks for your response, I will try code the above shortly. This is the product link sorry I posted the original manufacturers product link in the OP, https://core-electronics.com.au/rtc-pi.html

With regards to the lines, I have not taken this into account really because I just put the hat ontop of the Pi 4 the same way shown in the product page:

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Hi Oliver,

Product link correction: https://core-electronics.com.au/rtc-pi.html

Was hoping to get the one I purchased working instead.

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Hi Samuil,

Just to confirm since I’m getting myself up to speed on this problem, could you send through a photo of your hat on your Pi?

I’ve used a very similar board for my RTC on a project and had no issues getting it seen over i2c.

Keen to get to the bottom of this!
-James

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Hi James,

Your help would be much appreciated.

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Hi Samuil,

Apologies if this wasn’t clear in the product documentation, but you’ll need to solder the stacking headers onto your RTC board in order to get good continuity.

Once you’ve done this, let us know whether if you’re still having the same problems
-James

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Hi James,

Thank you for clarifying that I will take care of this later today when I return home.

While I have you, is it possible to trigger the RTC to turn on the Pi from ‘sleep’ or ‘hibernation’ ?

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Hi Samuil,

The functionality you’re looking for would be pretty hard for a simple RTC to do, you’d need some kind of microcontroller looking at the RTC and bridging a pin on the Pi to turn it on. By the way, the Pi has no true low-power state, the shutdown is actually a reboot that stops very early on in the boot process, and waits for a pin to continue.

While I believe the wake-on-pin functionality varies based on the Pi model, I’ve gotten it to work on a zero and I’ll check which pin it was when I get home.

-James

EDIT: 90% sure it was pins 5 and 6

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Thanks James much appreciated!

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if your worried i`d solder one of these to the rtc module pushing the pins right through as far as they can and solder the appropriate terminals then it becomes a proper stack-able unit…just straight out soldering to the rpi is not a good idea…seems to me what if you required it for another purpose …
this part.

i see it comes with the header yes solder it to the board it should be fine after that…i did not see its accessories til now…sozz…

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Good tip James :slight_smile: