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)

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Intel 8XC251SB, 8xC251TB, 8XC251SA XC251Tx Signal Descriptions Sheet 3, Description Alternate Name Function, Gnd, Wait#

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.

At the heart of the 8XC251 microcontrollers is the 8051 architecture, which provides a 16-bit processor capable of executing complex instructions efficiently. This architecture not only allows for a rich instruction set but also facilitates programming in assembly language and higher-level languages like C, which are essential for developing sophisticated embedded systems.

One of the significant features of the 8XC251 family is its integrated peripherals, including timer/counters, serial communication interfaces, and interrupt systems. These peripherals enable developers to implement timing functions, data communication, and real-time processing, all of which are crucial in modern embedded applications. The 8XC251SB and 8XC251SQ models, for instance, come equipped with multiple I/O ports that allow for interfacing with other devices and systems, enhancing their functionality in various environments.

The memory architecture of the 8XC251 devices is noteworthy, featuring on-chip ROM, RAM, and EEPROM. The on-chip memory allows for fast access times, which is essential for executing programs efficiently. Moreover, the EEPROM serves as non-volatile memory, enabling the storage of configuration settings and important data that must be retained even when power is lost.

In terms of operating voltage, the 8XC251 devices are designed to operate in a wide range, typically between 4.0V and 6.0V. This flexibility makes them suitable for battery-powered applications, where energy efficiency is critical. The power management features, including reduced power modes, further enhance their suitability for portable devices.

Lastly, the 8XC251 series is supported by a wide range of development tools and resources, allowing engineers and developers to streamline the development process. This support, combined with the microcontrollers' robust features, makes the Intel 8XC251 family a reliable choice for various embedded applications, such as industrial automation, automotive systems, and consumer electronics.

Overall, the Intel 8XC251SB, 8XC251SQ, 8XC251SA, and 8XC251SP deliver high performance, versatility, and ease of use, making them a preferred choice for embedded system designers looking to develop efficient and effective solutions.