Oscillation Halt Sensing Bit
The XSTP bit is for sensing a halt in the oscillation of the crystal oscillator. The oscillation halt sensing circuit
operates only when the CE pin is “L”.
· The XSTP bit will be set to 1 once a halt in the oscillation of the crystal oscillator is caused by such events as
power-on from 0 volts and a drop in supply voltage. The XSTP bit will hold the setting of 1 even after the restart of
oscillation. As such, the XSTP bit can be applied to judge the validity of clock and calendar data after power-on or
a drop in supply voltage.
· When the XSTP bit is set to 1, all bits will be reset to 0 in the oscillation adjustment register, control register 1,
and control register 2, stopping the output from the INTRA, INTRB, INTRC pin and starting the output of 32.768-
kHz clock pulses from the 32KOUT pin.
· The XSTP bit accepts only the writing of 0, which restarts the oscillation halt sensing circuit. Conversely, setting
the XSTP bit to 1 causes no event.
Sensing a normal condition of oscillation
Sensing a halt of oscillation
Enabling the 32-kHz clock output
Disabling the 32-kHz clock output
32-kHz Clock Output Bit 1
Setting the CLEN1 bit or the CLEN2 bit (D4 in control register 1) to 0, specifies generating clock pulses with the
oscillation frequency of the 32.768-kHz crystal oscillator for output from the 32KOUT pin. Conversely, setting both
the CLEN1 bit and the CLEN2 bit to 1 specifies disabling (“L”) such output.