8XC151SASB HIGH-PERFORMANCE CHMOS MICROCONTROLLER

Table 7 Signal Descriptions

(Continued)

Signal

Type

Description

Multiplexed

Name

With

GND

Circuit Ground

Connect this pin to ground

GND

Secondary Ground

This ground is provided to reduce ground bounce

and improve power supply bypassing Connection of this pin to ground

is recommended However when using the 8XC151SASB as a pin-

without loss of compatibility (Not available on DIP)

GND

Secondary Ground 2

This ground is provided to reduce ground

bounce and improve power supply bypassing Connection of this pin to

ground is recommended However when using the 8XC151SASB as

without loss of compatibility (Not available on DIP)

WR

O

Write

Write signal output to external memory

P36

XTAL1

I

Input to the On-chip Inverting Oscillator Amplifier

To use the

internal oscillator a crystalresonator circuit is connected to this pin If

an external oscillator is used its output is connected to this pin XTAL1

is the clock source for internal timing

XTAL2

O

Output of the On-chip Inverting Oscillator Amplifier

To use the

internal oscillator a crystalresonator circuit is connected to this pin If

an external oscillator is used leave XTAL2 unconnected

The descriptions of A158P270 and AD70P070 are for the nonpage-mode chip configuration (compatible with

44-lead PLCC and 40-pin DIP MCS 51 microcontrollers) If the chip is configured for page-mode operation port 0 carries

the lower address bits (A70) and port 2 carries the upper address bits (A158) and the data (D70)

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