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

// MSP430G2xx

// -----------------

// /|| XIN|-

// | | |

// --|RST XOUT|-

// | P1.6|-->LED

// | P1.0|-->LED

//

// Aldo Briano

// Texas Instruments, Inc

// June 2010

// Built with Code Composer Studio v4

//***************************************************************************************

#include <msp430g2231.h>

#define LED_0 BIT0

#define LED_1 BIT6

#define LED_OUT P1OUT

#define LED_DIR P1DIR

unsigned int timerCount = 0;

void main(void)

{

WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer

LED_DIR |= (LED_0 + LED_1); // Set P1.0 and P1.6 to output direction

LED_OUT &= ~(LED_0 + LED_1); // Set the LEDs off

CCTL0 = CCIE;

TACTL = TASSEL_2 + MC_2; // Set the timer A to SMCLCK, Continuous

// Clear the timer and enable timer interrupt

__enable_interrupt();

__bis_SR_register(LPM0 + GIE); // LPM0 with interrupts enabled

}

// Timer A0 interrupt service routine

#pragma vector=TIMERA0_VECTOR

__interrupt void Timer_A (void)

{

timerCount = (timerCount + 1) % 8;

if(timerCount ==0)

P1OUT ^= (LED_0 + LED_1);

}.

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