I have a customer who has conveyed the following "symptoms". I would like some guidance in debugging this issue:
The I2C interface appears to be working. Here are the symptoms:
- I can read and write every register. Data that is written, can be read back and makes sense compared to the Data Sheet.
- I can start and stop the internal oscillator.
- I can verify the oscillator drive to the crystal at about 700 mV, and the crystal voltage to the crystal input At about 600 mV. Is that correct?
- I can charge the supercap backup voltage supply. With a low voltage I do get an oscillator fail bit set when power off the RTC, which makes sense. With the supercap charged, I don’t get the OF indication through power-offs.
- The problem is that the RTC never updates any of the time related registers associated with it. Seconds or minutes never update from the initial value written to them.
- If the RTC is powered down then back up, the OF bit is not set, which makes sense and I get a new value in the seconds register that sometimes makes sense, but sometimes is 30 seconds or more off of what I expected. The minutes register appear sto sometimes not update as well.
- Until I cycle power, I never get any of the time registers to update, and once I read them, they never change again.
