Op-codes in Assembly Language are called as Mnemonics. Op-codes are in binary format used in Machine Language while the Mnemonic which are equivalent to Op-codes are English like statements. The second part of the instruction is called the Operand s and it represents the Data on which the operation is performed.
The Source Operand is the Input of the operation and the Destination Operand is where the result is stored. The last part of the Structure of Assembly Language is the Comments.
Comments are statements included by the developer for easier understanding of the code and is used for proper documentation of the Program. The following statements will show a few possible ways of using Label, Instruction and Comments. Assembly Language Directives are not the instructions to the Microcontroller Assembler even though they are written in the Mnemonic field of the program. Assembly Language Directives are actually instructions to the Assembler and directs the Assembler Program what to do during the process of Assembling.
We will now see about few of the important and frequently used Assembly Language Directives. This is also the address from which the Microcontroller will start executing the code.
Jump to MAIN. Hence, an entire chapter is devoted to explaining power management using One full-length design example explaining both hardware as well as software aspects of a home protection system using is presented as a case study. Discussions are concluded by a chapter on advanced microcontrollers such as the AVR. Add Comment. Save my name, email, and website in this browser for the next time I comment.
Rel: 2's complement 8-bit offset one - byte used for short jump SJMP and all conditional jumps. Assembly language Programming. Character transmission using a time delay:. A program shown below takes the character in 'A' register, transmits it, delays for transmission time, and returns to the calling program. Timer-1 is used to set the baud rate, which is baud in this program.
The delay for one character transmission in Mode 1 i. Or, 8. Hence software delay of 10ms is used. Timer-1 generates a baud rate close to Using a 12MHz crystal, the reload value is. This gives rise to an actual baud rate of SMOD is programmed to be 0. Operands: The operands are a single piece of data that can be operated by the op-code. Example, multiplication operation is performed by the operands that are multiplied by the operand.
Syntax: MUL a , b;. The assembling directives give the directions to the CPU. The microcontroller consists of various kinds of assembly directives to give the direction to the control unit.
The most useful directives are programming, such as:. ORG origin : This directive indicates the start of the program. This is used to set the register address during assembly. For example; ORG h tells the compiler all subsequent code starting at address h. DB define byte : The define byte is used to allow a string of bytes.
EQU equivalent : The equivalent directive is used to equate address of the variable. The way of accessing data is called addressing mode. The CPU can access the data in different ways by using addressing modes. The microcontroller consists of five addressing modes such as:.
It is used for immediately storing the value in the memory registers. In this addressing mode, the source and destination must be a register, but not general purpose registers.
So the data is not moved within the general purpose bank registers. In this addressing mode, the source or destination or both source and destination must be an address, but not value.
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