CHAPTER 5 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U13850EJ4V0UM
144
(3) Noise elimination of INTP6 pin
The INTP6 pin incorporates a digital noise eliminator. The sampling clock for digital sampling can be selected
from among f
XX
, f
XX
/64, f
XX
/128, f
XX
/256, f
XX
/512, f
XX
/1024, and f
XT
. Sampling is performed 3 times.
The noise elimination control register (NCC) selects the clock to be used. Remote control signals can be
received effectively with this function.
f
XT
can be used for the noise elimination clock. In this case, the INTP6 external interrupt function is enabled in
the IDLE/STOP mode.
This register can be read/written in 8- or 1-bit units.
Caution After the sampling clock has been changed, it takes sampling clock 3 clocks to initialize the
noise eliminator. For that reason, if an INTP6 valid edge was input within these 3 clocks, an
interrupt request may occur. Therefore, be careful of the following things when using the
interrupt and DMA functions.
••••
When using the interrupt function, after the sampling clock 3 clocks have elapsed, allow the
interrupt after the interrupt request flag (bit 7 of PIC6) has been cleared.
••••
When using the DMA function, after the sampling clock 3 clocks have elapsed, allow DMA
by setting bit 0 of DCHCn.
Figure 5-15. Noise Elimination Control Register (NCC)
After reset: 00H
R/W
Address: FFFFF3D4H
7
6
5
4
3
2
1
0
NCC
0
0
0
0
0
NCS2
NCS1
NCS0
Reliably eliminated noise width
Note 1
NCS2
NCS1
NCS0
Noise elimination
clock
f
XX
= 20 MHz
Note 2
f
XX
= 12.58 MHz
0
0
0
f
XX
100 ns
158 ns
0
0
1
f
XX
/64
6.4
µ
s
10.1
µ
s
0
1
0
f
XX
/128
12.8
µ
s
20.3
µ
s
0
1
1
f
XX
/256
25.6
µ
s
40.6
µ
s
1
0
0
f
XX
/512
51.2
µ
s
81.3
µ
s
1
0
1
f
XX
/1024
102.4
µ
s
162.7
µ
s
1
1
0
Setting prohibited
1
1
1
f
XT
61
µ
s
Notes 1.
Since sampling is preformed three times, the reliably eliminated noise width is 2
×
noise elimination
clock.
2.
Only for the V850/SB1.