HD404364 查看數據表（PDF） - Renesas Electronics

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HD404364

4-bit HMCS400-Series microcomputer

Renesas Electronics 

HD404369 Series

Notes on Usage

• Use the SEM or SEMD instruction for writing to the A/D start flag (ADSF)

• Do not write to the A/D start flag during A/D conversion

• Data in the A/D data register during A/D conversion is undefined

• Since the operation of the A/D converter is based on the clock from the system oscillator, the A/D

converter does not operate in stop, watch, or subactive mode. In addition, to save power while in these

modes, all current flowing through the converter’s resistance ladder is cut off.

• If the power supply for the A/D converter is to be different from VCC, connect a 0.1-µF bypass capacitor

between the AVCC and AVSS pins. (However, this is not necessary when the AVCC pin is directly

connected to the VCC pin.)

• The contents of the A/D data register are not guaranteed during A/D conversion. To ensure that the A/D

converter operates stably, do not execute port output instructions during A/D conversion.

• The port data register (PDR) is initialized to 1 by an MCU reset. At this time, if pull-up MOS is selected

as active by bit 3 of the miscellaneous register (MIS3), the port will be pulled up to VCC. When using a

shared R port/analog input pin as an input pin, clear PDR to 0. Otherwise, if pull-up MOS is selected by

MIS3 and PDR is set to 1, a pin selected by A/D mode register 1 or 2 (AMR1 or AMR2) as an analog

pin will remain pulled up (figure 78).

VCC

VCC

HLT

MIS3

AMR

A/D mode register value

DCR

Input control signal

PDR

CPU input

A/D input

ACR

A/D channel register value

Figure 78 R Port/Analog Multiplexed Pin Circuit

90

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