Renesas PCA7429G02 Technical Information PDF herunterladen (Seite 49)

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER

and ON-SCREEN DISPLAY CONTROLLER

M37272M6/M8–XXXSP/FP, M37272MA–XXXSP

M37272E8SP/FP, M37272EFSP

MITSUBISHI MICROCOMPUTERS

Rev. 1.3

8.8 A-D COMPARATOR

A-D comparator consists of 6-bit D-A converter and comparator. A-D

comparator block diagram is shown in Figure 8.8.1.

The reference voltage “Vref” for D-A conversion is set by bits 0 to 5 of

A-D control register 2 (address 00ED16).

The comparison result of the analog input voltage and the reference

voltage “Vref” is stored in bit 4 of A-D control register 1 (address

00EC16).

For A-D comparison, set “0” to corresponding bits of the direction

analog input pins to bits 0 to 2 of A-D control register 1 and write the

digital value corresponding to Vref to be compared to the bits 0

to 5 of A-D control register 2. The voltage comparison starts by writ-

ing to A-D control register 2, and it is completed after 16 machine

cycles (NOP instruction ✕ 8).

Fig. 8.8.1 A-D Comparator Block Diagram

A-D control register 1

Bits 0 to 2

Comparator control

Data bus

Bit 4

Switch tree

A-D control

Resistor ladder

Compa-

rator

Analog

signal

switch

Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

A-D control

AD1

AD2

AD3

AD4

AD5

AD6

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Renesas PCA7429G02 Technical Information Seite 49