Help with LED bargraph with sharp sensor *fixed*

Forum 2005-2010 (read only) Hardware Interfacing
1

OK, so I just got my arduino from robotshop.ca/arduino-experimentation-kit-hs422-gp2y0a02yk-3.html and I've started playing around. I really don't know what I'm doing but I took some code from different places and mashed it all together, but I'm not sure how to code the last part.

Most of the code came from the bar graph example, but here it is:

// these constants won't change:
const int IRpin = 1;    // the pin that the potentiometer is attached to
const int ledCount = 6;    // the number of LEDs in the bar graph

int ledPins[] = { 
  2, 3, 4, 5, 6, 7 };   // an array of pin numbers to which LEDs are attached


void setup() {
  // loop over the pin array and set them all to output:
  Serial.begin(9600);    // start the serial port
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT); 
  }
}

void loop() {
  float volts = analogRead(IRpin)*0.0048828125;   // value from sensor * (5/1024) - if running 3.3.volts then change 5 to 3.3
  float distance = 65*pow(volts, -1.10);          // worked out from graph 65 = theretical distance / (1/Volts)S - luckylarry.co.uk
  Serial.println(distance);
  delay(100);

  // I know this isn't right.

  // loop over the LED array:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    // if the array element's index is less than ledLevel,
    // turn the pin for this element on:
    if (distance > 30) {
      digitalWrite(ledPins[thisLed], HIGH);
    } 
    if (distance > 40) {
      digitalWrite(ledPins[thisLed], HIGH);
    }
    if(distance > 50) {
      digitalWrite(ledPins[thisLed], HIGH);
    }
    if(distance > 60) {
      digitalWrite(ledPins[thisLed], HIGH);
    }
    if(distance > 70) {
      digitalWrite(ledPins[thisLed], HIGH);
    }
    if(distance > 80) {
      digitalWrite(ledPins[thisLed], HIGH);
    }
    // turn off all pins higher than the ledLevel:
    else {
      digitalWrite(ledPins[thisLed], LOW); 
    }
  }
}
2

I'm not sure how to code the last part.

What do you think "the last part" is?

We can only guess.

3

Whoops, the last part starts with // Iknow this isn't right
and ends at the end of the code.

4

And what do you know to be "right"?

5

I know that the sensor works for sure because I'm using that same code in some other stuff:

void loop() {
  float volts = analogRead(IRpin)*0.0048828125;   // value from sensor * (5/1024) - if running 3.3.volts then change 5 to 3.3
  float distance = 65*pow(volts, -1.10);          // worked out from graph 65 = theretical distance / (1/Volts)S - luckylarry.co.uk
  Serial.println(distance);
  delay(100);

but I'm not really sure about anything else :cry:

6

I just realized that my LEDs were actually hooked up to 5v instead of ground, shakes head I'll test it and tell you if it works

7

ok, I got it to work now, I guess all I had to do was actually look at it.

Here's the updated code:

// these constants won't change:
const int IRpin = 1;    // the pin that the potentiometer is attached to
const int ledCount = 6;    // the number of LEDs in the bar graph

int ledPins[] = { 
  2, 3, 4, 5, 6, 7 };   // an array of pin numbers to which LEDs are attached


void setup() {
  // loop over the pin array and set them all to output:
  Serial.begin(9600);    // start the serial port
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT); 
  }
}

void loop() {
/*  // read the potentiometer:
  int sensorReading = analogRead(analogPin);
  // map the result to a range from 0 to the number of LEDs:
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);
*/

  float volts = analogRead(IRpin)*0.0048828125;   // value from sensor * (5/1024) - if running 3.3.volts then change 5 to 3.3
  float distance = 65*pow(volts, -1.10);          // worked out from graph 65 = theretical distance / (1/Volts)S - luckylarry.co.uk
  Serial.println(distance);
  delay(100);

  // loop over the LED array:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    // if the array element's index is less than ledLevel,
    // turn the pin for this element on:
    if (distance > 30) {
      digitalWrite(ledPins[0], HIGH);
    } 
    if (distance > 40) {
      digitalWrite(ledPins[1], HIGH);
    }
    if(distance > 50) {
      digitalWrite(ledPins[2], HIGH);
    }
    if(distance > 60) {
      digitalWrite(ledPins[3], HIGH);
    }
    if(distance > 70) {
      digitalWrite(ledPins[4], HIGH);
    }
    if(distance > 80) {
      digitalWrite(ledPins[5], HIGH);
    }
    // turn off all pins higher than the ledLevel:
    else {
      digitalWrite(ledPins[thisLed], LOW); 
    }
  }
}

Now I just need to edit some stuff to make it better. Thanks for the help ;D