Let`s assume we are trying to develop an application using MSP430 with the follo

Question

Let`s assume we are trying to develop an application using MSP430 with the following specications. When the push button (connected to P1.3 on the MSP430 LaunchPad) is pressed four times, the red LED (connected to P1.0 on the MSP430 LaunchPad) will turn on and the green LED (connected to P1.6 on the MSP430 LaunchPad) will turn off. When the push button is pressed two more times, the red LED will turn off and the green LED will turn on. This procedure is repeated indenitely.

Draw the wring diagram of microcontroller application.

Write a C program for the application.

Explanation / Answer

#include #define LED_0 BIT0 #define LED_1 BIT6 #define LED_OUT P1OUT #define LED_DIR P1DIR #define BUTTON BIT3 unsigned int blink = 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 P1REN |= BUTTON; //Enables a puller-Resistor on the button-pin P1OUT |= BUTTON; //Writes a "1" to the portpin, tellling the resistor to pullup P1IES |= BUTTON; //Triggers when you PRESS the button :: Pick one... //P1IES &= ~BUTTON; // Triggers when you RELEASE the button :: ...or pick the other P1IE |= BUTTON; //Enables the selector-mask for generating interrupts on the relevant pin __enable_interrupt(); // Interrupts get enabled *here* - they were disabled thus far.. for (;;) { if(blink > 0) { P1OUT ^= (LED_0 + LED_1); // Toggle P1.0 and P1.6 using exclusive-OR __delay_cycles(100000); // SW Delay of 10000 cycles at 1Mhz } } } // Port 1 interrupt service routine #pragma vector=PORT1_VECTOR __interrupt void Port_1(void) { blink ^= 0x01; P1IFG &= ~BUTTON; // P1.3 IFG cleared LED_OUT &= ~(LED_0 + LED_1); // Clear the LEDs so they start in OFF state }

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