1 Reply Latest reply on Nov 27, 2018 6:43 AM by rcarter_3886506

    FM31256 RTC Oscillator Startup

    rcarter_3886506

      I am using a FM31256 in a design and cannot get the RTC oscillator to start.

       

      We are able to read and write values, such as CAL, W, and R at address 0x00 of the RTC. We are also able to read and write the FRAM memory, so feel our I2C functions and interface is working correctly.

       

      We are unable, however, to clear the OSCEN bit at address 0x01, or clear the POR and LB bits at address 0x09 to get the RTC oscillator started. The OSCEN, POR, and LB bits are defaulting "SET" during powerup, which appears normal, but we are unable to clear them.

       

      Have scoured the datasheet, app notes, and forum, but not seeing what might be precluding clearing those bits and getting the RTC oscillator to start.

       

      Any ideas?