R01UH0136EJ0210 Rev.2.10
Page 187 of 800
Jul 31, 2012
M16C/64A Group
13. Programmable I/O Ports
13.4.3
NMI
/
SD
Digital Filter
The
NMI
/
SD
input function includes a digital filter. A sampling clock can be selected by bits NMIDF2 to
NMIDF0 in the NMIDF register. The
NMI
level is sampled for every sampling clock. When the same
sampled level is detected three times in a row, the level is transferred to the internal circuit.
When using the
NMI
/
SD
digital filter, do not enter wait mode or stop mode.
Port P8_5 is not affected by the digital filter.
Figure 13.13 shows
NMI
/
SD
Digital Filter, and Figure 13.14 shows
NMI
/
SD
Digital Filter Operation
Example.
Figure 13.13
NMI
/
SD
Digital Filter
Figure 13.14
NMI
/
SD
Digital Filter Operation Example
13.4.4
CNVSS Pin
The built-in pull-up resistor of the CNVSS pin is activated after watchdog timer reset, hardware reset,
power-on reset, or voltage monitor 0 reset. Thus, the CNVSS pin outputs a high-level signal up to two
cycles of fOCO-S. Connect the CNVSS pin to VSS via a resistor to use it in single-chip mode.
Digital Filter
CPU clock
Divider
PM24
NMIDF2 to NMIDF0
Sampling clock
NMIDF2 to NMIDF0
Other than 000b
000b
NMI interrupt
SD input
P8_5 input
PM24: Bit in the PM2 register
NMIDF2 to NMIDF0: Bits in the NMIDF register
P8_5/
NMI
/
SD
/CEC
CEC input
The above diagram assumes bits NMIDF2 to NMIDF0 in the NMIDF register are set to a value
other than 000b (NMI/SD filter enabled).
NMI/SD pin
NMI/SD input
Sampling timing
Level matches three times
An NMI interrupt is generated when the PM24 bit in
the PM2 register is 1 (NMI interrupt enabled).
Содержание M16C/60 Series
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