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Intel 8XC251SQ, 8XC251SA, 8XC251SP, 8XC251SB manual SP Contents, SP.70 Stack Pointer

Models: Embedded Microcontroller 8XC251SP 8XC251SA 8XC251SQ 8XC251SB

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REGISTERS

SCON

Address:

98H

 

Reset State:

0000 0000B

Serial Port Control Register. SCON contains serial I/O control and status bits, including the mode select bits and the interrupt flag bits.

 

7

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

FE/SM0

SM1

 

SM2

 

REN

 

 

TB8

 

RB8

 

TI

RI

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

Bit

 

 

 

 

 

 

Function

 

 

 

 

 

Number

Mnemonic

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

TI

Transmit Interrupt Flag Bit:

 

 

 

 

 

 

 

 

 

 

 

Set by the transmitter after the last data bit is transmitted. Cleared by

 

 

 

 

 

software.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

RI

Receive Interrupt Flag Bit:

 

 

 

 

 

 

 

 

 

 

 

Set by the receiver after the last data bit of a frame has been received.

 

 

 

 

 

Cleared by software.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SP

 

 

 

 

 

 

 

 

 

 

Address:

S:81H

 

 

 

 

 

 

 

 

 

 

 

 

Reset State:

0000 0111B

 

Stack Pointer. SP provides SFR access to location 63 in the register file (also named SP). SP is the lowest byte of the extended stack pointer (SPX = DR60). The extended stack pointer points to the current top of stack. When a byte is saved (PUSHed) on the stack, SPX is incremented, and then the byte is written to the top of stack. When a byte is retrieved (POPped) from the stack, it is copied from the top of stack, and then SPX is decremented.

7

 

0

 

 

SP Contents

 

 

 

 

 

 

Bit

Bit

Function

Number

Mnemonic

 

 

 

 

7:0

SP.7:0

Stack Pointer:

Bits 0–7 of the extended stack pointer, SPX (DR60).

C-25

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Intel 8XC251SQ, 8XC251SA, 8XC251SP, 8XC251SB, Embedded Microcontroller manual SP Contents, SP.70 Stack Pointer
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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.