MSP430 button and LED demo

blink.c

 /***********************************************************
  *    TI MSP-430 LaunchPad Button & LED-Blinking Demo
  *
  * Simple example of using a button to manipulate LEDs.
  *
  * Pressing the button (P1.3) will toggle a pattern of the
  * red/green LEDs alternating on/off.
  *
  * Tested on an MSP430G2231, built with mspgcc toolchain.
  **********************************************************/
#include <io.h>
#include <signal.h>

#define BUTTON   BIT3 // Port 1.3
#define REDLED   BIT0 // Port 1.0
#define GRNLED   BIT6 // Port 1.6

int doflip = 1;

int main(void) {
  // Watchdog setup
  WDTCTL = WDTPW + WDTHOLD; // stop watchdog (password + hold counter)

  // LED initial setup
  P1DIR |= REDLED + GRNLED;             // set P1.0 and P1.6 as output (1) pins
  P1OUT |= REDLED;                      // Enable REDLED
  P1OUT &= ~GRNLED;                     // Disable GRNLED

  // Button setup
  P1DIR &= ~BUTTON;                     // button is an input
  P1OUT |= BUTTON;                      // pull-up resistor
  P1REN |= BUTTON;                      // resistor enabled
  P1IES |= BUTTON;                      // interrupt on low-to-high transition
  P1IE |= BUTTON;                       // interrupt enable

  // Timer setup
  BCSCTL3 |= LFXT1S_2;                  // Set clock source to VLO
  TACCR0 = 2500;                        // Count to this, then interrupt
  TACTL = TASSEL_1 | MC_1;              // Clock source ACLK
  TACCTL1 = CCIE;                       // Timer A interrupt enable

  // Shut down CPU, General Interrupt Enabled
  __bis_SR_register(CPUOFF | GIE);
  return 0;
}

interrupt(TIMERA1_VECTOR) ta1_isr(void) {
  TACCTL1 &= ~CCIFG;                    // reset the interrupt
  if (doflip)
    P1OUT ^= (REDLED + GRNLED);         // flip LED output
}

interrupt(PORT1_VECTOR) port1_isr(void) {
  P1IFG = 0;                            // reset interrupt
  doflip ^= 1;                          // toggle LED flipping
}

tjo

tjo