7721 datasheet(19/577 Pages) RENESAS

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DESCRIPTION

7721 Group User’s Manual

1–4

1.3 Pin description

Tables 1.3.1 to 1.3.3 list the pin description.

Table 1.3.1 Pin description (1)

1.3 Pin description

Vcc, Vss

CNVss

______

RESET

________

RESETOUT

XIN

XOUT

BYTE

ST0

ST1

AVcc

AVss

VREF

Input/Output

Input

Output

Input

Output

Input

Output

Input

ST1

ST0

Bus use state

DRAM refresh

Hold

DMA

CPU

Functions

Supply 5 V ±10 % to Vcc pin and 0 V to Vss pin.

Connect to Vss or Vcc pin.

The microcomputer is reset when supplying “L” level

to this pin.

______

When input to RESET pin is “L,” this pin outputs “L.”

Output from this pin returns “H” after the release of

reset. When writing “1” to the software reset bit, this

pin outputs “L.”

These are I/O pins of the internal clock generating

circuit. Connect a ceramic resonator or quartz-crystal

oscillator between pins XIN and XOUT. When using an

external clock, the clock source should be input to XIN

pin and XOUT pin should be left open.

Data/instruction code read or data write is performed

when output from this pin is “L” level.

Input level to this pin determines whether the external

data bus has a 16-bit width or an 8-bit width. The

width is 16 bits when the level is “L”, and 8 bits when

the level is “H”.

The bus use state is output in 2-bit code.

The power supply pin for the A-D converter. Connect

AVcc to Vcc pin. Connect AVss to Vss pin.

This is a reference voltage input pin for the A-D converter.

Name

Power supply

CNVss

Reset input

Reset output

Clock input

Clock output

Enable output

Exernal data bus width

selection input

Status signal output

Analog supply input

Reference voltage input

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