UPD78F0138 NEC, UPD78F0138 Datasheet - Page 258

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

(4) Power-fail comparison mode register (PFM)
(5) Power-fail comparison threshold register (PFT)
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Caution If data is written to PFM, a wait cycle is generated. Do not write data to PFM when the CPU is
Caution If data is written to PFT, a wait cycle is generated. Do not write data to PFT when the CPU is
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.
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.
operating on the subsystem clock and the X1 input clock is stopped. For details, see CHAPTER
34 CAUTIONS FOR WAIT.
operating on the subsystem clock and the X1 input clock is stopped. For details, see CHAPTER
34 CAUTIONS FOR WAIT.
Figure 12-7. Format of Power-Fail Comparison Threshold Register (PFT)
Address: FF2AH
Symbol
Address: FF2BH
Symbol
Figure 12-6. Format of Power-Fail Comparison Mode Register (PFM)
PFM
PFT
PFEN
PFEN
PFT7
<7>
0
1
0
1
7
Stops power-fail comparison (used as a normal A/D converter)
Enables power-fail comparison (used for power-fail detection)
Higher 8 bits of
ADCR
Higher 8 bits of
ADCR < PFT
Higher 8 bits of
ADCR
Higher 8 bits of
ADCR < PFT
PFCM
PFCM
After reset: 00H
After reset: 00H
PFT6
<6>
6
CHAPTER 12 A/D CONVERTER
PFT
PFT
User’s Manual U16228EJ2V0UD
PFT5
5
0
5
Power-fail comparison enable
Interrupt request signal (INTAD) generation
No INTAD generation
No INTAD generation
INTAD generation
PFT4
R/W
R/W
4
0
4
Power-fail comparison mode selection
PFT3
3
0
3
PFT2
2
0
2
PFT1
1
0
1
PFT0
0
0
0