Instruction Set Architecture (ISA) specifies the instructions that a microprocessor can execute. It can be viewed as a programmer's manual. It clearly defines everything needed for writing either a compiler or machine language program for a microprocessor supporting particular ISA. The ISA itself does not contain hardware implementations details. There can be microprocessors with different
The arithmetic logic unit (ALU) is at the hearth of the microprocessor. It is designed to perform both arithmetic and logical operations on integer binary numbers. Principle of operation The ALU does not need a clock signal as it is a pure combinational digital circuit. The output will change asynchronously in response to change on the
The microprocessor (also known as Central Processing Unit(CPU) ) is a computational machine. It executes arithmetic, logical, control and input/output operations. It is programmable and follows the instructions programmed into its memory. Principle of Operation In order for the processor to perform the task required by a particular instruction, it follows a process called the instruction
Addressing Mode refers to the way the actual location of an instruction's operand is specified. It is used in the decode phase of the instruction cycle to extract the operand of the instruction so the proceeding execute phase can start. The main purpose of having different addressing modes is to provide flexibility when referencing the memory location of
The microprocessor (also known as Central Processing Unit (CPU)) can be defined simply as a calculation machine. It executes predefined operations called instructions. The steps the CPU performs in order to execute an instruction is called an instruction cycle (also known as fetch-execute cycle or fetch-decode-execute cycle). Understanding the instruction cycle is a great starting point for
A microprocessor instruction is a description of an operation that has to be performed on a data. The data is called operand. An instruction may have one or more operands. The microprocessor executes instructions in a process called instruction cycle. Each microprocessor is designed to operate on a specific set of instructions defined in its instruction set
The program counter (PC) is a register that is part of the central processing unit (CPU). It contains the memory address for the next instruction that has to be executed during the instruction cycle of the microprocessor. Principle of Operation Each instruction cycle begins by accessing the instruction stored at the address that is pointed by
Overview Speaking in general a bootloader is any piece of code that is executed before the main application code starts. In this article we will focus on a particular type of a bootloader - one that is used to erase the code of the main application from the flash memory and program it with a
Writing programs for embedded systems often requires the manipulation of individual bits. Below is a list of the most common operations. In the examples we are performing them on an unsigned long variable called ctrl_reg. Setting a bit We can set a bit using the bitwise OR operator (|): ctrl_reg |= 1UL << n; The
Overview There are two major types of memory system architectures when it comes to executing code in embedded systems: Execute in Place (XIP): The program code is executed directly from a flash memory. Store and Download (SnD) : The program code is stored in a non-volatile memory but is copied to RAM during the boot up
