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Addition of n byte using microcontroller

Aim: Write an Assembly language program to add ‘n’ bytes stored in external memory (Starting address 4000 and number of bytes is 5) and store output at 3020H.

Apparatus Used: Micro-controller kit.

Assumption:  In this program we have to add n bytes number. Means there are 5 numbers which are stored at different memory location; we have store output at 3020 H.
Algorithm:

• Load number of bytes in Register R0.
• Initialize R1 as 00.
• Initialize memory location to store input at memory location.
• Move the first number into accumulator.
• Now add R1 to accumulator.
• Increase pointer to point next number.
• Repeat this till R2=00
• Initialize memory location to store output.
• Store output at given location. 

Program:

Description of used instruction:

MOV: Used for Load and Copy the Data. This copies a byte from the source location to destination. 

INC DPTR: This instruction increments the 16-bit register DPTR (Data Pointer) by 1. Notice that DPTR is the only 16-bit register that can be incremented. 

ADD: This adds the source byte to the accumulator and keeps result in accumulator. 

DJNZ: In this instruction a byte is decremented, and if result is not zero it will jump to the target address.

MOVX: This instruction transfer data between external memory and register. 

DPTR: This is Data Pointer. It is used for containing 16 bit data or memory address. 

SJMP: Short Jump loop is used for indefinite loop within program.

Result:

Input:    4000-01H

              4001-03H

              4002-02H

              4003-01H

              4004-04H        

Output:  0BH and it will store at external memory 3020H.

Procedure to look output:

·         After ending (SJMP) the program, press Enter two times.

·         You will get message “Welcome to ------KIT”.

·         Press G and Provide initial address of program as in this program, starting address is 3000 H.

·         Press Enter.

·         After pressing Enter, You will get Message “Execution Completed”.

·         Press Reset on micro-controller KIT.

·         Press M and You will get Message “Enter Address”.

·         Provide Location of Input as in this program 4000H. Press Space and write a number as first input,press Space again and enter 2nd input as so on for 5 inputs.

·         Press Enter two times again.

·         Press G and provide starting address (3000H)  and Press Enter.

·         You will Get Message “Execution Completed”.

·         Press M and You will Get Message “Enter Address”.

·         Provide Address for Output as in this Program 3020H and Press Space and you get Output.

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