M41T83ZMY6F RTC Reports Half the Actual Time

[shan]

I am working with the M41T83ZMY6F RTC (internal crystal version) in a project and I’ve encountered an unusual behavior: when I read the time via I²C, the RTC seems to count at exactly half the expected rate. For example, after one real second, the seconds register increments by 0.5 s equivalent (or appears to update only every 2 seconds).

Interestingly, I have observed that on some boards the RTC works correctly, while on others it exhibits this half-speed behavior.

What can cause this ?

Thanks

[Mike_ST]

Hello,

In that kind of case, it can be a good idea to dump the registers, and compare working vs non-working case.

You can even post the registers values, perhaps someone will have an idea.

[TDK]

It's probably also a good idea to show your evidence of the issue. What leads you to believe time is slowing down on some chips? Perhaps there is some other explanation.

[shan]

After writing the system time to the RTC in Linux, when I read the RTC time from the Linux terminal after a while, I observe that the RTC is behind the system time by exactly half of the elapsed time.

Thanks