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I think my interrupt isn't working; Code Help

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Hello there,



I am doing a project where I have to read in a square wave and determine the frequency of the wave then output that number.

I found out that I am using a 1MHz clock, then I set up an interrupt to count the edges for my square wave input.  I don't think my interrupt is working though.  I even changed it to a push button and tried to get it to turn on led's it didn't work.


ps. I'm using energia btw.

pps. I'm using msp430 revision 1.5


Hope someone can help me out


Thanks a bunch!!


if you don't know what energia is energia.nu is where you can find information


My code so far

int ledPin0 = 3;// select the pin for the LED
int ledPin1 = 4;
int ledPin2 = 5;
int ledPin3 = 6;
int ledPin4 = 8;

volatile int sensorPin = A7; // select the input pin for the potentiometer

volatile int temp=0;
//int count=0;
volatile int count1=0;
volatile int number=0;
void setup() {
// declare the ledPin as an OUTPUT:
pinMode(ledPin0, OUTPUT);
pinMode(ledPin1, OUTPUT);
pinMode(ledPin2, OUTPUT);
pinMode(ledPin3, OUTPUT);
pinMode(ledPin4, OUTPUT);
pinMode(sensorPin, INPUT_PULLUP);


void loop() {
if (analogRead(sensorPin == HIGH)){
  count1 = count1++;
  number = count1;
  count1 =0;

//Check for Frequency
//number = 1000000/count1;

//Make temp Variable to change
temp = number;

//Coverts that number to binary
//Checks if it need to turn on light 5
if(temp >= 16){
digitalWrite(ledPin4, HIGH);
temp = temp - 16;
digitalWrite(ledPin4, LOW);
//Checks for light 4
if(temp >= 8){
digitalWrite(ledPin3, HIGH);
temp = temp-8;
digitalWrite(ledPin3, LOW);
//Checks for light 3
if(temp >= 4){
digitalWrite(ledPin2, HIGH);
temp = temp - 4;
digitalWrite(ledPin2, LOW);
//Checks for light 2
if(temp >= 2){
digitalWrite(ledPin1, HIGH);
digitalWrite(ledPin1, LOW);
//Checks for light 1
if(temp >= 1){
digitalWrite(ledPin0, HIGH);
digitalWrite(ledPin0, LOW);
//count1 =0;
//Interuppt Routine
//void inter()
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make sure that you input pin is pulled up. You can do this with pinMode(sensorPin, INPUT_PULLUP);

Also note that A5 is indicating an analog channel. A5 when using it in any of the digital API's translates to pin 5 which is P1.3.

So rather than using int sensorPin = A5; I suggest that you use uint16_t sensorPin = P1_3.

Since count is being increased in the interrupt routine, you will need to make it a volatile. Simply said, volatile means that the value can change at any time. so that would be volatile uint8_t count1;


Below is a small example that will toggle the red LED when the button is pushed.

int pin = RED_LED;
volatile int state = LOW;

void setup()
  pinMode(pin, OUTPUT);
  attachInterrupt(PUSH2, blink, CHANGE);

void loop()
  digitalWrite(pin, state);

void blink()
  state = !state;

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Ok, I just updated the code, still isn't working.  Does the fact that i'm getting an actual signal and not a digital one mean I need to go about checking the edges differently?


also @@energia I tried the code you posted and it didn't make the light blink, When i hit the button nothing happens.  Maybe my board is messed up?

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