SIGNAL DESCRIPTIONS

P1.0 / T2

P1.1 / T2EX

P1.2 / ECI

P1.3 / CEX0

P1.4 / CEX1

P1.5 / CEX2

P1.6 / CEX3 / WAIT#

P1.7 / CEX4 / A17 / WCLK RST P3.0 / RXD

P3.1 / TXD

P3.2 / INT0#

P3.3 / INT1#

P3.4 / T0

P3.5 / T1

P3.6 / WR#

P3.7 / RD# / A16

XTAL2

XTAL1

VSS

1

 

40

2

 

39

3

 

38

4

 

37

5

8XC251SA

36

6

35

8XC251SB

7

8XC251SP

34

8

8XC251SQ

33

9

 

32

10

 

31

11

 

30

12

 

29

13

View of

28

14

27

15

component

26

as mounted

16

25

on PC board

17

24

 

18

 

23

19

 

22

20

 

21

VCC

AD0 / P0.0

AD1 / P0.1

AD2 / P0.2

AD3 / P0.3

AD4 / P0.4

AD5 / P0.5

AD6 / P0.6

AD7 / P0.7

EA# / VPP

ALE / PROG#

PSEN#

A15 / P2.7

A14 / P2.6

A13 / P2.5

A12 / P2.4

A11 / P2.3

A10 / P2.2

A9 / P2.1

A8 / P2.0

A4206-03

Figure B-2. 8XC251SA, SB, SP, SQ 40-pin PDIP and Ceramic DIP Packages

Table B-2. Signal Descriptions

Signal

Type

Description

Alternate

Name

Function

 

 

 

 

 

 

A17

O

Address Line A17. Eighteenth external address bit (A17) in

P1.7/CEX4/

 

 

extended bus applications. Selected by configuration byte

WCLK

 

 

UCONFIG0, bits RD1:0 (Table B-3). Also see RD# and PSEN#.

 

 

 

 

 

A16

O

Address Line A16. Seventeenth external address bit (A16) in

P3.7/RD#

 

 

extended bus applications. Selected by configuration byte

 

 

 

UCONFIG0, bits RD1:0 (Table B-3). Also see RD#.

 

 

 

 

 

A15:8†

O

Address Lines. Upper address lines for the external bus.

P2.7:0

AD7:0†

I/O

Address/Data Lines. Multiplexed lower address lines and data

P0.7:0

 

 

lines for external memory.

 

 

 

 

 

ALE

O

Address Latch Enable. ALE signals the start of an external bus

PROG#

 

 

cycle and indicates that valid address information is available on

 

 

 

lines A15:8 and AD7:0. An external latch can use ALE to

 

 

 

demultiplex the address from the address/data bus.

 

 

 

 

 

†The descriptions of A15:8/P2.7:0 and AD7:0/P0.7:0 are for the nonpage mode chip configuration (com- patible with 44-pin PLCC and 40-pin DIP MCS®51 microcontrollers). If the chip is configured for page mode operation, port 0 carries the lower address bits (A7:0), and port 2 carries the upper address bits (A15:8) and the data (D7:0).

B-3

Page 394 Page 396
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Image 395
Intel 8XC251SA, 8XC251SB, Embedded Microcontroller manual 8XC251SP 8XC251SQ, Component As mounted On PC board
Page 394 Page 396

Embedded Microcontroller, 8XC251SP, 8XC251SA, 8XC251SQ, 8XC251SB 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.
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