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MS430G2452 REV1.5 Issues

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I'm trying to run this general code to blink the led and be able to turn it off and on with the following code.

#include "msp430g2452.h"
#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


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



The button doesn't do anything because REV1.5 is missing the R34 and C24 which is connected to P1.3.

This website https://github.com/energia/Energia/wiki/Hardware states to add something like this to fix the problem.

pinMode(PUSH2, INPUT); becomes pinMode(PUSH2, INPUT_PULLUP); or pinMode(P1_3, INPUT); becomes pinMode(P1_3, INPUT_PULLUP);


How would I implement this into this existing code???

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Also what does volatile mean?


It's a way of forcing the compiler into not "optimizing" the variable "blink".

Sometimes the compiler becomes too smart, thinks that the variable isn't really used, so it codes around it.

By using Volatile, you are telling the compiler that the Blink variable can change on it's own, so it needs to always read the value of blink from memory instead.

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