M16C65 Datasheet, PDF (123/829 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M16C/60

Under development
M16C/65 Group
Preliminary Specification
This is a preliminary specification and is subject to change.
7. Voltage Detector
7.4 Operations
7.4.1 Digital Filter
A digital filter can be used to monitor VCC1 input voltage. For the voltage detection i circuit (i = 0 to 2),
the digital filter is enabled when the VWiC1 bit in the VWiC register is set to 0 (digital filter enabled).
The fOCO-S divided by 1, 2, 4, or 8 is selected as a sampling clock. When using the digital filter, set the
CM14 bit in the CM1 register to 0 (125 kHz on-chip oscillator on).
The VCC1 input level is sampled by the digital filter for every sampling clock. When the same sampled
level is detected two times in a row, at the next sampling timing, the internal reset signal goes low or a
voltage monitor i interrupt request is generated. Therefore, when the digital filter is used, the time from
when the VCC1 input voltage level passes Vdeti until when a reset or an interrupt is generated is up to
three cycles of the sampling clock.
Since the fOCO-S stops in stop mode, the digital filter does not function. When using the voltage
detection i circuit to exit stop mode, set the VWiC1 bit in the VWiC register to 1 (digital filter disabled).
Figure 7.2 shows Digital Filter Operation Example.
VCC1
Vdet1
Up to 3 cycles of the sampling clock
Up to 3 cycles of the sampling clock
VW1C3 bit in
the VW1C register
Sampling timing of
the digital filter
VW1C2 bit in
the VW1C register
Internal signal
(Voltage monitor 1
interrupt request)
Set to 0 by a program
The above diagram applies to the following cases:
•The VW12E bit in the VWCE register is 1 (voltage detection 1 and 2 circuits enabled).
•The VW1C0 bit in the VW1C register is 1 (voltage monitor 1 interrupt/reset enabled).
•The VW1C1 bit in the VW1C register is 0 (digital filter enabled).
•The VW1C6 bit in the VW1C register is 0 (voltage monitor 1 interrupt at Vdet1 passage).
Figure 7.2 Digital Filter Operation Example
REJ09B0484-0030 Rev.0.30 Sep 09, 2008
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