RTC not recognized

[vidrazor]

I've been wanting to add a clock backup for a Pi5 and I purchase a DS3231 RTC Module for it. I plugged into inner pins 13579 on the Pi, and went through the instruction here on how to set it up. So I booted and typed "sudo i2cdetect -y 1", and got the same number 68 as in your example.

However, when I went to add the ds3231 number to the dtoverlay=i2c-rtc in the config.txt file, ds3231 was already there.

So according to the instructions, I should be seeing UU when I type in sudo i2cdetect -y 1, because ds3231 was already there. All I get however is the number 68.

So is the RTC board I got not compatible with the Pi 5? The board I got is this one:

https://www.amazon.com/dp/B08X4H3NBR?th=1

Thanks for your time.

[vidrazor]

So do I take it that you can't use a DT3231 board on a Pi 5?

[Jimbob-B]

I'm not sure if I'll be much help as I've not tried running astroarch on my pi5 but couple of things I can think of when reading your question are,

• The Pi5 has a built in RTC and I think you will find this will be assigned /dev/rtc0 and your DS3231, when recognized, will be /dev/rtc1. What is listed under /dev/rtc* now? The linux kernel is usually coded to pickup rtc0 as the default and, from what I can see when messing about with a Tinkerboard, you can't easily change it to use rtc1 unless you recompile the whole kernel and change the default RTC setting.
• That module should work fine ... I have a similar one running on my StellarMate install that I purchased from thepihut.com. This is a Pi4 that I dual boot between StellarMate and AstroArch. I would check what the kernel is recognising for rtc devices by using dmesg | grep -i rtc. You should see entries for both the Pi5 RTC and the DS3231 module. The kernel messages may help debug what is happening to cause the issues you're seeing. The Pi5 rtc0 module will look something like this,

[    0.258946] rpi-rtc soc:rpi_rtc: trickle charging enabled at 3000000uV
[    0.264144] rpi-rtc soc:rpi_rtc: registered as rtc0
[    0.265527] rpi-rtc soc:rpi_rtc: setting system clock to 2025-02-22T15:56:05 UTC (1740239765)

This is assuming the Arch Linux kernel recognizes the Pi5 RTC.