(1) At first power-up, the time registers have gibrish values in them, and the UBOOT (initial code that is running during boot) needs to have special code to update them before the Linux driver can even access it. Usually RTC is supposed to wake up with some initial value (that is not gibrish). (2) We have two more devices on the I2C bus: ADT7461ARMZ and M24C32-RMB6TG. There's a 1Kohm pull-up on SDA and SCL signals. (3) We read the data from the RTC using an application called HWCLOCK (version 2.13). We also use a Linux driver for the BQ32000 that first appeared in version 2.6.34 of the Linux Kernel. We had to add a 50usec delay in the driver, after each access to the seven time registers in the device. Without this delay HWCLOCK fails to perform the access correctly (read or write). The other devices on the I2C bus work fine. (4) Without connecting a battery the device wouldn't start. A mandatory connection of a battery (or other voltage source) to Vback pin is not mentioned in the datasheet.
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