Solve the following problems using the MSP430 IAR Compiler/Assembler . Setup the

Question

Solve the following problems using the MSP430 IAR Compiler/Assembler.   

Setup the MSP430 LaunchPad to use Timer A to toggle the red LED each time the timer counts to 50,000. You should be able to do this using:

A- An assembly language program that calls a subroutine to configure Timer to toggle the LED every 50,000 cycles.

B- An assembly language program that sets up an interrupt from Timer A every 50,000 cycles.

C- Repeat the above part B but this time develop a mixed language program that calls the assembly language subroutines from the C language.

Additional requirements:

- For the above problems that combine C and assembly, the input data should be declared in the C portion of the program.

- For the above problems that only use assembly language, the input data should be stored in RAM.

- Code needed to test each problem should be included.

Explanation / Answer

STATUS          equ       03h            ;Address of the STATUS register
TRISA             equ       85h           ;Address of the tristate register for port A
PORTA            equ       05h            ;Address of Port A
COUNT1          equ       08h            ;First counter for our delay loops
COUNT2          equ       09h            ;Second counter for our delay loops

;****Set up the port****

bsf                  STATUS,5       ;Switch to Bank 1
movlw              00h                ;Set the Port A pins
movwf              TRISA            ;to output
bcf                  STATUS,5       ;Switch back to Bank 0

;****Turn the LED on****

Start            movlw            02h          ;Turn the LED on by first putting it
                   movwf           PORTA       ;into the w register and then on the port

;****Add a delay

          call                   Delay

;****Delay finished, now turn the LED off****

movlw              00h                ;Turn the LED off by first putting it
movwf              PORTA           ;into the w register and then on the port

;****Add another delay****

call                   Delay

;****Now go back to the start of the program
                     goto          Start      ;go back to Start and turn LED on again

;****Here is our Subroutine

Delay

Loop1          decfsz              COUNT1,1     ;This second loop keeps the LED
                  goto                 Loop1          ;turned off long enough for us to
                  decfsz              COUNT2,1     ;see it turned off
                  goto                 Loop1          ;
return

;****End of the program****

end                     ;Needed by some compilers, and also

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