The destination register to which the constant data must be copied should be the same size as the operand mentioned in the instruction. The constant value to be stored is specified in the instruction itself rather than taking from a register. The name Immediate Addressing came from the fact that the constant data to be stored in the memory immediately follows the Opcode. In Immediate Addressing mode, the operand, which follows the Opcode, is a constant data of either 8 or 16 bits. The 8051 Family of Microcontrollers allows five types of Addressing Modes for addressing the Operands. There are 49 Instruction Mnemonics in the 8051 Microcontroller Instruction Set and these 49 Mnemonics are divided into five groups.Ĩ051 Addressing Modes What is an Addressing Mode?Īn Addressing Mode is a way to locate a target Data, which is also called as Operand. The following table shows the 8051 Instruction Groups and Instructions in each group. A Brief Look at 8051 Microcontroller Instructions and Groupsīefore going into the details of the 8051 Microcontroller Instruction Set, Types of Instructions and the Addressing Mode, let us take a brief look at the instructions and the instruction groups of the 8051 Microcontroller Instruction Set (the MCS-51 Instruction Set). As a result, the 8051 Microcontroller instruction set can have up to 2 8 = 256 Instructions.īefore going into details of 8051 Microcontroller Instruction Set, read this: 8051 MICROCONTROLLER MEMORY ORGANIZATION. As a typical 8-bit processor, the 8051 Microcontroller instructions have 8-bit Opcodes. This tutorial introduces the 8051 Microcontroller Instruction Set also called as the MCS-51 Instruction Set.Īs the 8051 family of Microcontrollers are 8-bit processors, the 8051 Microcontroller Instruction Set is optimized for 8-bit control applications. Instructions written in a program tell the Microcontroller which operation to carry out.Īn Instruction Set is unique to a family of computers. Just as our sentences are made of words, a Microcontroller’s (for that matter, any computer) program is made of Instructions. The commands to the Microcontroller are known as a Microcontroller’s Instruction Set. Writing a Program for any Microcontroller consists of giving commands to the Microcontroller in a particular order in which they must be executed in order to perform a specific task.
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Introduction to 8051 Microcontroller Instruction Set
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A Brief Look at 8051 Microcontroller Instructions and Groups.Introduction to 8051 Microcontroller Instruction Set.