HD404459 Datasheet, PDF (100/122 Pages) Renesas Technology Corp – 4-bit HMCS400-series microcomputers

HD404459 Series
Comparator enable register (CER: $017)
Bit
Initial value
Read/Write
Bit name
3
0
R
CER3
2
0
W
CER2
1
0
W
CER1
0
0
W
CER0
CER1
0
1
CER0
0
1
0
1
Analog input mode selection
COMP₀
COMP₁
COMP₂
COMP₃
CER2
0
1
Reference power supply selection
External reference power supply
Internal reference power supply
CER3
0
1
Voltage comparison result
Analog input voltage is lower than
reference voltage
Analog input voltage is higher than
reference voltage
Figure 81 Comparator Enable Register (CER)
Comparator Start Flag (CMSF: $020, Bit 2): Starts the comparator operation. The comparator starts the
voltage comparison by writing 1 to the comparator start flag (CMSF: $020, bit 2), and automatically
completes the voltage comparison after 4t_cyc. The comparator start flag is then reset to 0. The comparison
result must be read after confirming that the comparator start flag is at 0. The comparator start flag is reset
to 0 by MCU reset.
Notes on Use: RA₀/COMP₀–RA₃/COMP₃ pins are used only for the comparator during voltage comparison.
These pins cannot be used for R ports.
The comparator operates only in the active and standby modes.
The switch for the internal power supply is turned on when the internal power supply is selected. The
switch is turned off except in active and standby modes.
When the external power supply is used for a reference voltage, R9₃/VC_ref must not be used as an R port.
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