Intel 8XC251SB XC251Tx Signal Descriptions Sheet 3, Description Alternate Name Function, Gnd

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8xC251Tx Hardware Description

 

 

Table 2. 8xC251Tx Signal Descriptions (Sheet 3 of 3)

 

 

 

 

 

Signal

Type

Description

Alternate

Name

Function

 

 

 

 

 

 

VCC2

PWR

Secondary Supply Voltage 2. This supply voltage connection is pro-

 

 

 

vided to reduce power supply noise. Connection of this spin to the

 

 

 

+5V supply voltage is recommended. However, when using the ZX3

 

 

 

as a pin for pin replacement for the 8XC51FX, VCC2 can be uncon-

 

 

 

nected without loss of compatibility (Not available on DIP).

 

 

 

 

 

VSS

GND

Circuit Ground. Connect this pin to ground.

 

VSS1

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 ZX3 as a pin

 

 

 

for pin replacement for the 8XC51FX, VSS1 can be unconnected with-

 

 

 

out loss of compatibility. (Not available in DIP).

 

 

 

 

 

VSS2

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 ZX3 as a pin

 

 

 

for pin replacement for the 8XC51FX, VSS1 can be unconnected with-

 

 

 

out loss of compatibility. (Not available in DIP).

 

 

 

 

 

WAIT#

I

Real-time Wait State Input. The real-time WAIT# input is enabled by

P1.6/CEX3

 

 

writing a logical "1" to the WCON.0 (RTWE) bit at S:A7H. During bus

 

 

 

cycles, the external memory system can signal ‘system ready’ to the

 

 

 

microprocessor in real time by controlling the WAIT# input signal

 

 

 

 

 

WCLK

O

Wait Clock Output. The real-time Wait Clock output is driven by writ-

P1.7/CEX4/

 

 

ing a logical "1" to the WCON.1 (RTWCE) bit at S:A7H. When

A17

 

 

enabled, the WCLK output produces a square wave signal with a

 

 

 

period of one-half the oscillator frequency

 

 

 

 

 

WR#

O

Write. Write signal output to external memory. Asserted for the mem-

P3.6

 

 

ory address range specified by configuration byte UCONFIG0, bits

 

 

 

RD1:0.

 

 

 

 

 

XTAL1

I

Input to On-chip, Inverting Oscillator Amplifier. To use the internal

 

 

 

oscillator, a crystal/resonator 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 the internal timing

 

 

 

 

 

XTAL2

O

Output of the On-chip, Inverting Oscillator Amplifier. To use the

 

 

 

internal oscillator, a crystal/resonator circuit is connected to this pin. If

 

 

 

an external oscillator is used, leave XTAL2 unconnected.

 

 

 

 

 

*The descriptions of A15:8/P2.7:0 and AD7:0/P0.7:0 are for non page mode configuration. If configured in page mode, Port 0 carries the lower address bits (A7:0) and Port 2 carries the upper address bits (A15:8) and the data (D7:0)

5

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Contents 8xC251TB, 8xC251TQ, Hardware Description Page Description DateDecember 273138-002 8xC251TB, 8xC251TQ Hardware Description 8xC251Tx Hardware Description OTPROM/EPROM XC251Tx Block DiagramProcessor Control Name XC251Tx Signal SummaryPower & Ground Name Address & Data NameAddress Line 16. See RD# XC251Tx Signal Descriptions Sheet 1Signal Type Description Alternate Name Function Timer 10 External Clock Inputs. When Timer 10 operates as a XC251Tx Signal Descriptions Sheet 2GND XC251Tx Signal Descriptions Sheet 3Signal Description Alternate Name FunctionCH00000 CCAP0Hx CCAP1Hx CCAP2Hx CCAP3Hx CCAP4Hx Xxxxxxx Special Function Register SFR MapFunction Type Description Multiplexed Second Serial I/O Port SignalsMnemonic Description Address Second Serial I/O Port Special Function RegistersBit Number Function Mnemonic Bit Number Bit Mne Function Monic IPH1.0 IPL1.0 Priority Level Bit NumberExtended Data Float Timings UCONFIG1 bit definitions for the 8xC251TxInterrupt Mode Reserved for Internal or Future UseWSB#10 Wait State Extended Data Float Summary of the EDF# and WSB#10 Configuration Options
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8XC251SP, 8XC251SA, 8XC251SQ, 8xC251TB, 8xC251TQ specifications

The Intel 8XC251 series of embedded microcontrollers is a family of versatile and powerful devices, designed to meet the demands of a wide range of applications. With models such as the 8XC251SB, 8XC251SQ, 8XC251SA, and 8XC251SP, this series offers unique features while maintaining a high level of performance and reliability.

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