HD404459 Datasheet, PDF (97/122 Pages) Renesas Technology Corp – 4-bit HMCS400-series microcomputers

HD404459 Series
Comparator
The comparator (figure 78) compares an analog input voltage with a reference voltage. Either a 16-level
internal or external reference power supply can be selected.
The voltage comparison is started by writing 1 to the comparator start flag (CMSF: $020, bit 2), and is
completed after 4t_cyc. The comparison result is stored into bit 3 (CER: $017, bit 3) of the comparator enable
register, and can be read by the bit test instruction (TM or TMD). The comparison result must be read after
confirming that the comparator start flag (CMSF: $020, bit 2) is at 0 (figure 79).
Internal data bus
4
Comparator
control register
(CCR)
4
1
Comparator
start flag
(CMSF)
1
3
1
Comparator
enable register
(CER)
1
2
R9₃/VC_ref
RA₀/COMP₀
RA₁/COMP₁
RA₂/COMP₂
RA₃/COMP₃
COMP
Figure 78 Block Diagram of Comparator
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