Given: BF548 with MERCURY X3215-32.768K crystal connected to the RTC.
Normally, the RTC ticks OK, but under some not exactly understood conditions (generally speaking, under high CPU activity) the RTC ticks way way fast!!
It can make extra 20 sec in one minute! If I observe signal on the RTXO pin - it is always 32768 Hz.
Unfortunately, I cannot see what is going on the RTXI pin, because the generation fades when I touch it by the probe.
Have somebody run into something like this??