8.3 Operation Description
8.3.1 Configuration
The noise filter circuit consists of the noise filter circuit and interrupt request generation circuit.
It eliminates high level or low level noise from external inputs and then CG detects the rising/falling edge
or signal level (high or low) to determine the signal state in each interrupt signal.
8.3.2 Operation
The noise filter eliminates high and low level noise from the external interrupt input INTx.
A noise filtering time is determined by the input level continuation time specified in NFCKCR<NFCKS>.
If the time is less than 7 clocks, the input is determined as noise. If the time is over 8 clocks, the input is deter-
mined as an invalid signal. However, the determination of an input signal for 7 to 8 clocks varies depending
on the edge timing.
8.3.3 Noise Filter Usable Operation Mode
The noise filter circuit can be used only in the NORMAL mode and IDLE mode.
8.3.4 Precautions on Use of STOP Mode
If STOP mode is used, the noise filter circuit cannot be used due to a stop of fsys clock. If external input
are used to release STOP mode, set the following procedure: Set the interrupt enable bit to be disabled; set
the noise filter enable/disable bit of NFENCR register; and stop the noise filter clock of NFCKCR register.
8.3.5 Minimum Noise Filtering Time
The noise filter circuit determines input levels to send the external interrupt signals if high level or low lev-
el inputs are continued to input over 8 clock periods specified in NFCKCR register.
Table 8-1 Minimum noise filtering time
NFCKCR<NFCKS>
fsys [MHz]
Unit
20
32
40
001
0.7
0.44
0.35
μs
010
1.4
0.88
0.7
011
2.8
1.75
1.4
100
5.6
3.5
2.8
101
11.2
7.0
5.6
110
22.4
14.0
11.2
111
44.8
28.0
22.4
TMPM3V6/M3V4
8. Digital Noise Filter Circuit (DNF)
8.3 Operation Description
Page 132
2019-02-06
Summary of Contents for TMPM3V4
Page 1: ...32 Bit RISC Microcontroller TX03 Series TMPM3V6 M3V4 ...
Page 2: ... 2019 Toshiba Electronic Devices Storage Corporation ...
Page 7: ...Revision History Date Revision Comment 2019 02 06 1 First Release ...
Page 8: ......
Page 22: ...xiv ...
Page 52: ...TMPM3V6 M3V4 3 Processor Core 3 6 Exclusive access Page 30 2019 02 06 ...
Page 148: ...TMPM3V6 M3V4 7 Exceptions 7 6 Exception Interrupt Related Registers Page 126 2019 02 06 ...
Page 178: ...TMPM3V6 M3V4 9 Input Output port 9 2 Block Diagrams of Ports Page 156 2019 02 06 ...
Page 354: ...TMPM3V6 M3V4 14 Synchronous Serial Port SSP 14 6 Frame Format Page 332 2019 02 06 ...
Page 419: ...TMPM3V6 M3V4 Page 397 2019 02 06 ...
Page 462: ...TMPM3V6 M3V4 21 Watchdog Timer WDT 21 5 Control register Page 440 2019 02 06 ...
Page 544: ......