Xycom XVME-113, User Manual

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Chapter 3 – Real Time Clock
3-10
Follow the procedure below to initialize the RTC after initial power is applied:
1. The TEST bit (bit 3 of Control Register B) is undefined after initial power up. Therefore,
calendar/clock operation is also undefined. Set the TEST bit to '0' before continuing with
initialization.
2. Delay for 3 seconds before continuing with initialization. This time is required for oscillator
stabilization within the RTC chip.
3. Since interrupts from the RTC are not used on the XVME-113, clear the CIE (bit 4 of Control Register
A) and AIE (bit 3 of Control Register A) bits to '0'.
4. The Start/Stop bit (bit 0 of Control Register B) is undefined at power-up. This bit should be cleared
to '0' to stop the clock in order for the time to be set.
3.5.2
Time Setting Procedure
There are two ways that the RTC time can be set. If the date and time are to be set from scratch, the clock should be
stopped. This is the easiest way for the RTC time to be set. Alternatively, RTC registers can be set while the clock is
running. Both methods are described in the following sections.