arduino count (simple C question)

Hi Dani

You need a flag to show whether you are counting up or down.

Here is a little sketch to illustrate a possible solution:

/*

  demonstrate up down counter

  Neil Kenyon 01 February 2014

  Public domain

*/

int count = 0;                   // counter value

int upperLimit = 180;      // Upper limit

int lowerLimit = 0;           // Lower limit

boolean up = true;          // Counter direction flag

                                          // true says "countup"; false says "count down"

void setup()

{

  Serial.begin(9600);  

}

void loop()

{

  Serial.println(count);

  Serial.println(up);                   // This will show 1 for true and 0 for false

  if (up ) {                                    // Only do this if we are counting up

    if (count < upperLimit ) {

      count = count + 10;

      if (count == upperLimit) {    // Reached upper limit

        up = false;                           // Set the flag false to count down

      }

    }

  }

  else if (count > lowerLimit) {

    count = count - 10;

    if (count == lowerLimit) {      // Reached lower limit

      up = true;                              // Set the flag false to count down

    }

  }

  delay(500); 

}

I hope this helps

Best wishes

Neil

thanks so much

ill try as soon as possible

it makes so sense

do you have a web side book that teach the very basic of arduino c programming language

I feel that even if I follow the tutorial in the arduino starter kit book I don't have the right background in C to over come issue that I found when I want to do something different then the tutorial.

cheeeeers

D

Dani

I'm not a trained C programmer either. However, I have worked through ALL of Jeremy Blum's Tutorials, as well as lots of others you can find in the web.

You'll soon pick it up.

Neil

Dani

There have been many questions posted in the past regarding tutorials, with some good suggestions.

You should be able to use the search function to find them.

do you have a web side book that teach the very basic of arduino c programming language

IT eBooks - Free Download - Big Library

you should find a number there to download.

I'd suggest this one Arduino Cookbook, 2nd Edition - Free Download eBook - pdf

There is an example in the Arduino IDE called BASICS - Fade

/*
 Fade

 This example shows how to fade an LED on pin 9
 using the analogWrite() function.

 This example code is in the public domain.

 */
int brightness = 0;    // how bright the LED is
int fadeAmount = 5;    // how many points to fade the LED by

void setup()  { 
  // declare pin 9 to be an output:
  pinMode(9, OUTPUT);
} 

void loop()  { 
  // set the brightness of pin 9:
  analogWrite(9, brightness);    

  // change the brightness for next time through the loop:
  brightness = brightness + fadeAmount;

  // reverse the direction of the fading at the ends of the fade: 
  if (brightness == 0 || brightness == 255) {
    fadeAmount = -fadeAmount ; 
  }     
  // wait for 30 milliseconds to see the dimming effect    
  delay(30);                            
}

In this they basically change the value of the 'step' from the default of 5 to -5 (see line 27).

As you can see there are several different ways to achieve the same result, some are faster than others but with a delay of 500 or 1000 who cares.

You should also look at the example 'BlinkWithoutDelay' for methods of slowing down a process without using the delay function.

This allows you to do other things while you're waiting. ie check an input.

Mark

thanks for all the info

fantastic forum

I want to learn more and more

I'll post many other question soon

cheers

D

Another solution to consider (angleForced = val)

int direction = 1;

int val = 180;

void loop()

{

   if (val == 0 || val == 180)

   {

         direction = direction * -1;

   }

   val = val + (10 * direction);

}

hi

looks like a very elegant solution

can you add same explanation on every line?

cheers

d

Well, you start with 180 before going into the loop then in the loop:

- whenever the value gets down to zero or up to 180 you want to change direction so the direction is either 1 or -1

- now you update the value by adding ten each time going in the loop and factor in the direction

- if the direction is positive (1) then the value goes up (and eventually hit 180)

- if the direction is negative (-1) then the value goes down (and eventually hit 0)

Cheers

thanks for your time