milli second timer?

Forum 2005-2010 (read only) Hardware Interfacing
1

I am trying to make a timer that activates when one ir beam is broken then stop when a second beam is broken. The two beams are one inch apart, so with time and distance I can calculate speed(chronograph). Im not shure on how to go about making this timer, does anyone have any suggestions for me on how to program the timer, I can do everything else.

Thanks

2

So what your saying I should do is store the value in the EEPROM, and just read that value once the second beam breaks?

3

This is the code so far: Any tips?

int ir1 = 5;
int ir2 = 4;
int ir1val;
int ir2val;
int rawms;
int differance;
void setup(){
  Serial.begin(115200);
}

void loop(){
  ir1val = analogRead(ir1);
  ir2val = analogRead(ir2);
 
  if(ir2val < 1000){

    differance = micros();
  }
  if(ir1val < 1000){
    rawms = micros() - differance;
    Serial.println(rawms, DEC);
    delay(1000);
}
}
4 
int ir1 = 5;
int ir2 = 4;
int ir1val;
int ir2val;
[glow]unsigned long[/glow] rawms;
[glow]unsigned long[/glow] differance;

void setup(){
  Serial.begin(115200);
}

void loop(){
  ir1val = analogRead(ir1);
  ir2val = analogRead(ir2);

  if( (ir2val < 1000) [glow]&& (ir1val >= 1000)[/glow] ){

    differance = micros();
  }
  if( (ir1val < 1000) [glow]&& (ir2val >= 1000)[/glow] ){
    rawms = micros() - differance;
    Serial.println(rawms, DEC);
    delay(1000);
}
}
5

Thanks bud, I got it from here.