CHAPTER 12 A/D CONVERTER
User’s Manual U16899EJ2V0UD
253
(4) Power-fail
comparison
mode register (PFM)
The power-fail comparison mode register (PFM) is used to compare the A/D conversion result (value of the
ADCR register) and the value of the power-fail comparison threshold register (PFT).
PFM can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Figure 12-7. Format of Power-Fail Comparison Mode Register (PFM)
0
0
0
0
0
0
PFCM
PFEN
Power-fail comparison enable
Stops power-fail comparison (used as a normal A/D converter)
Enables power-fail comparison (used for power-fail detection)
PFEN
0
1
Power-fail comparison mode selection
Interrupt request signal (INTAD) generation
No INTAD generation
INTAD generation
No INTAD generation
Higher 8 bits of
ADCR
≥
PFT
Higher 8 bits of
ADCR < PFT
Higher 8 bits of
ADCR
≥
PFT
Higher 8 bits of
ADCR < PFT
PFCM
0
1
0
1
2
3
4
5
<6>
<7>
PFM
Address: FF2AH After reset: 00H R/W
Symbol
Caution If data is written to PFM, a wait cycle is generated. Do not write data to PFM when the CPU is
operating on the subsystem clock and the high-speed system clock is stopped. For details, see
CHAPTER 32 CAUTIONS FOR WAIT.
(5) Power-fail comparison threshold register (PFT)
The power-fail comparison threshold register (PFT) is a register that sets the threshold value when comparing the
values with the A/D conversion result.
8-bit data in PFT is compared to the higher 8 bits (FF09H) of the 10-bit A/D conversion result.
PFT can be set by an 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Figure 12-8. Format of Power-Fail Comparison Threshold Register (PFT)
PFT0
PFT1
PFT2
PFT3
PFT4
PFT5
PFT6
PFT7
0
1
2
3
4
5
6
7
PFT
Address: FF2BH After reset: 00H R/W
Symbol
Caution If data is written to PFT, a wait cycle is generated. Do not write data to PFT when the CPU is
operating on the subsystem clock and the high-speed system clock is stopped. For details, see
CHAPTER 32 CAUTIONS FOR WAIT.
Содержание MuPD78F0132H
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