HD404669 Datasheet, PDF (98/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
Comparator
The MCU has a built-in comparator that compare an input voltage with the reference voltage (V_Cref). The
comparator block diagram is shown in figure 76.
The comparator can operate in active mode and subactive mode. They are halted in other modes.
COMP₀
COMP₁
VC_ref
+
Comparator
-
Compare data
register (CDR)
2
Compare enable
register (CER)
Figure 76 Comparator Block Diagram
Comparator Operation
(1) Analog input pin selection is performed by bits 0 and 1 (CER0, CER1) of the compare enable
register (CER). Setting bit 3 (CER3) to 1 places the RD₀/COMP₀ and RD₁/COMP₁ pins in analog
input mode and starts comparator operation. While comparator operation is in progress, none of
these pins (including pins not used for comparison) can be used as R port pins.
(2) The compare result can be read by means of a bit test instruction (TM or TMD) on the compare data
register (CDR) bit corresponding to the selected analog input pin.
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