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Intel 8XC251SB, 8XC251SA, 8XC251SP, 8XC251SQ manual Source Mode or Binary Mode Opcodes

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

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CHAPTER 5

PROGRAMMING

The instruction set for the MCS® 251 architecture is a superset of the instruction set for the MCS® 51 architecture. This chapter describes the addressing modes and summarizes the instruc- tion set, which is divided into data instructions, bit instructions, and control instructions. Appen- dix A, “Instruction Set Reference,” contains an opcode map and a detailed description of each instruction. The program status words PSW and PSW1 are also described.

NOTE

The instruction execution times given in Appendix A are for code executing from on-chip code memory and for data that is read from and written to on- chip RAM. Execution times are increased by executing code from external memory, accessing peripheral SFRs, accessing data in external memory, using real time wait states, using RD#/WR#/PSEN# preprogrammed wait states, or extending the ALE pulse.

For some instructions, accessing the port SFRs (Px, x = 3:0) increases the execution time. These cases are noted individually in the tables in Appendix A.

5.1SOURCE MODE OR BINARY MODE OPCODES

Source mode and Binary mode refer to the two ways of assigning opcodes to the instruction set of the MCS 251 architecture. Depending on the application, one mode or the other may produce more efficient code. The mode is established during device reset based on the value of the SRC bit in configuration byte UCONFIG0. For information regarding the selection of the opcode mode, see section 4.6, “Opcode Configurations (SRC).”

5.2PROGRAMMING FEATURES OF THE MCS® 251 ARCHITECTURE

The instruction set for MCS 251 microcontrollers provides the user with new instructions that ex- ploit the features of the architecture while maintaining compatibility with the instruction set for MCS 51 microcontrollers. Many of the new instructions operate on 8-bit, 16-bit, or 32-bit oper- ands. (In comparison with 8-bit and 16-bit operands, 32-bit operands are accessed with fewer ad- dressing modes.) This capability increases the ease and efficiency of programming MCS 251 microcontrollers in a high-level language such as C.

The instruction set is divided into data (refer to section 5.3, “Data Instructions”), bits (see section 5.4, “Bit Instructions”), and control instructions (see section 5.5, “Control Instructions”). Data in- structions process 8-bit, 16-bit, and 32-bit data; bit instructions manipulate bits; and control in- structions manage program flow.

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Intel 8XC251SB, 8XC251SA, 8XC251SP Source Mode or Binary Mode Opcodes, Programming Features of the MCS 251 Architecture
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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.