Coin Selector by Using Arduino

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dondon pramis
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Location: Philippines
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Coin Selector by Using Arduino

Tue Mar 12, 2019 6:00 pm

For your Coin Selector to know what type of coins it accepts, you have to set it up and then feed it samples of those coins. It is recommend to sample at least 15 coins of the same type, up to a maximum of 30. Don't feed the same coin through 30 times, it's make the selector to fussy about what it accepts.

A Coin Selector works by comparing the material, weight and size of coins past through it to the samples you provide. If a coin is not recognized it drops out the return slot, if it is recognised the Unit sends out pulse's on the "COIN" line.

So to make it easier for the programming side we use a "greatest common factor" rule. e.g. We'll use the following coins (UK) 5p, 10p, 20p, 50p,& £1, (US) 5c, 10c, 25c, 50c & $1.
All the the coins can be made up with multiple 5p or 5c coins, so we make 1 pulse equal to 5p or 5c. 5p/c = 1 pulse, 10p/c = 2 pulses, 20p = 4 pulses, 25c = 5 pulses, 50p/c = 10 pulses, £/$1 = 20 pulses.
Coin-Selector.jpg
Now, The Setup:

First the switches...
select "NC" by sliding the top switch to the bottom position.
select "FAST" by sliding the bottom switch to the top position.

Power Up the unit with a 12v supply.

1. Hold the "ADD" and "MINUS" buttons down at the same time for about 3 seconds, release and then the letter "A" will appear on the LED display.
2. Press the "SETUP" button once, and the letter "E" will appear. Then use the "ADD" and "MINUS" buttons to choose how many kinds of coins your going to use. Press the "SETUP" button again to finish.
3. The letter "H" will appear. Use the "ADD" and "MINUS"buttons to choose how many sample coins your going to feed it later. Press the"SETUP" button again to finish.
4. The letter "P" will appear. Again use the "ADD" and "MINUS" buttons to choose the amount of output pulses you want. Press the "SETUP" button to finish. Refer to the above example to determine number of pulses.
5. The letter "F" will appear. Using the "ADD" and "MINUS" buttons, choose the accuracy. The value is from 1 to 30, with 1 being the most accurate. I use 10 and it works fine. Again "SETUP" to finish.

You have now setup the first coin, depending on how many coins you selected in step 2, you'll have to repeat Step's 3 to 5 for each one.
The letter "A" will appear when you've setup all the coins. Hold "SETUP" for 3 seconds to finish, the letter "E" will appear.
Finally, switch the unit off and then back on.

Sampling time:

1. Hold the "SETUP" button down for about 3 seconds, release and then the letters "A1" will appear on the LED display. This is your first coin (5p/c)
2. Feed the Coin Selector your sample coins, the LED display will show the amount of coins you've entered. "A1" will appear again when finished.
3. Hold the "SETUP" button down again for about 3 seconds, release and then"A2" will appear, repeat these steps until all coins are sampled.

If your not using all of the coin types available (eg 5 coins of a 6 type coin selector) the unit will ask for samples of a coin type you haven't setup, just hold the "SETUP" button down for 3 secconds of each of the remaining coins.

The Coin Selector restarts itself and is now ready to connect to the Arduino.

To Wire the Coin Selector to the Arduino is easy.

The white "COIN" Wire from the Selector connects to pin 2 on the Arduino. It has to be pin 2 or 3 as these are Interrupt pins.

Now if your using a different power supply for the Coin Selector to the Arduino, you must connect a common Ground. So the Red wire from the Coin Selector connects to +12V of the supply and the Black wire to ground of the supply AND to ground of the arduino.

Note: USB will NOT power the coin selector.

Code:

Code: Select all

const int coinInt = 0; 
//Attach coinInt to Interrupt Pin 0 (Digital Pin 2). Pin 3 = Interrpt Pin 1.

volatile float coinsValue = 0.00;
//Set the coinsValue to a Volatile float
//Volatile as this variable changes any time the Interrupt is triggered
int coinsChange = 0;                  
//A Coin has been inserted flag

void setup()
{
  Serial.begin(9600);                 
//Start Serial Communication
  attachInterrupt(coinInt, coin Inserted, RISING);   
//If coinInt goes HIGH (a Pulse), call the coin Inserted function
//An attachInterrupt will always trigger, even if your using delays
}

void coinInserted()    
//The function that is called every time it receives a pulse
{
  coinsValue = coinsValue + 0.05;  
//As we set the Pulse to represent 5p or 5c we add this to the coins Value
  coinsChange = 1;                           
//Flag that there has been a coin inserted
}

void loop()
{
  if(coinsChange == 1)          
//Check if a coin has been Inserted
  {
    coinsChange = 0;              
//unflag that a coin has been inserted
  
    Serial.print("Credit: $");
    Serial.println(coinsValue);    
//Print the Value of coins inserted
  }
}
This simple program will write the total value of coins inserted to the serial monitor.
If you'd like your project to start automatically after say 50p or 50c has been inserted then replace:

Serial.print("Credit: $");
Serial.println(coinsValue);
with:

if(coinsValue >= 0.50)
{
//your code here, eg Big Flashing Lights!!!! and Serial.println("Received Money");
}
Continue if you want to Interface with a Window Application

Load up Microsoft Express 2010 and create a new "Windows Form Application".
I'm calling mine Coin Selector.

Now to your form add the following components:
1. A Button, Change the Text to "Connect"
2. A Text Box, Change the Text to "0.00"
3. A Serial Port, Change the PortName to the COM Port your Arduino connects to.

Coding

Code: Select all

Double Click the "Connect" Button and you'll open the Code window, paste the following code in the brackets:

if (button1.Text == "Connect")   //If the button say's connect
            {
                 serialPort1.Open();             //Open Serial Port
                 if (serialPort1.IsOpen)         //If the Port Opens
                 {
                     button1.Text = "Disconnect";    //Change the Button to Disconnect
                     this.serialPort1.DataReceived += new System.IO.Ports.SerialDataReceivedEventHandler(this.serialPort1_DataReceived);
      //Adds an Event when the serial port receives data
                 }           
            }
            else
            {
                serialPort1.Close();            //Close the Serial Port
                button1.Text = "Connect";    //Change the Button to Connect
            }

We have to add a few functions, the first will close the port if we close the application. The second tells the program what to do if data is received and the third is what it does. So Just below the final "}" of "button1_Click" add the following:

Code: Select all

//CLOSE PORT ON EXIT
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (serialPort1.IsOpen)
            {
                serialPort1.Close();
            }
        }

//SERIAL DATA RECEIVED EVENT
        private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {   //serialPort1 runs in a different thread, to call a function in the main code Invoke must be used
            this.Invoke(new EventHandler(serialReceived));  //Calls the below function
        }
        private void serialReceived(object sender, EventArgs e)
        { 
                double coinsValue = Convert.ToDouble(textBox1.Text);  //converts the text to a number
                coinsValue = coinsValue + 0.05;          //Add 0.05 to that number
                textBox1.Text = Convert.ToString(coinsValue);     //Converts it back to text and puts it back in the textbox          
        }

Now, Scroll up and you'll see some "using" lines, add "using System.IO.Ports;" as we'll be using Serial port functions.

The Basic Program is finished, On the Arduino side:
replace...
    Serial.print("Credit: $");
    Serial.println(coinsValue);
with...
  Serial.print(0);  //Sends 1 piece of data over the Serial, the windows program add's 0.05 for every piece (println would send 3)
Upload, Run the windows Application, Click "Connect" and your away!


You can now activate your projects by receiving the right amount of money! lol


User avatar
Delo Ramci
Posts: 17
Joined: Thu Jan 26, 2017 12:17 pm

Re: Coin Selector by Using Arduino

Tue Mar 12, 2019 6:39 pm

I ran into a pretty big problem with static electricity in my application. Sometimes you could shock the front plate and it would count for a pulse or two, giving you false money. I modified the code slightly. You'll also need to set each coin to pulse one more time than normal. For instance, make nickles pulse 2 times instead of one. Then use this code:
const int coinInt = 0;
//Attach coinInt to Interrupt Pin 0 (Digital Pin 2). Pin 3 = Interrpt Pin 1.
int oldMillis = 0; //set first old time to 0
volatile float coinsValue = 0.00;
//Set the coinsValue to a Volatile float
//Volatile as this variable changes any time the Interrupt is triggered
int coinsChange = 0;

//A Coin has been inserted flag
int currentMillis = 0; //define currentMillis
void setup()
{
Serial.begin(9600);

//Start Serial Communication

attachInterrupt(coinInt, coinInserted, RISING);

//If coinInt goes HIGH (a Pulse), call the coinInserted function
//An attachInterrupt will always trigger, even if your using delays

}
void coinInserted()
//The function that is called every time it recieves a pulse

{

//As we set the Pulse to represent 5p or 5c we add this to the coinsValue
coinsChange = 1;
unsigned long currentMillis = millis(); //check current time
int difference = currentMillis-oldMillis; //find difference between last pulse time //and current pulse time

//Serial.print("Millis: ");
//Serial.println(difference);
oldMillis = currentMillis; //set old pulse time
if(difference < 152 && difference >148){

//unless the pulse time was in between the numbers above, it won't count for //money
coinsValue = coinsValue +0.05;
coinsChange = 1;
}

//Flag that there has been a coin inserted
}

void loop()
{
if (coinsChange == 1){
Serial.print("Money: $");
Serial.println(coinsValue);
coinsChange = 0;
}
}

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