Dog-controlled treat dispenser part 2

This is the second part of my project to create a dog treat dispenser that my dog, Jack, can operate on his own. For the first part, click here.

Building an enclosure
I thought about 3d-printing an enclosure for the control box, but before I commit the time and effort to designing and printing one, I want to make sure that the project works - and that Jack actually uses it.
So for now, I've managed to fit the electronics into an old business card box, with basic cut outs for the buttons and wiring. It's not pretty, but it works.

The enclosure (the croc clips are for power - final version recycled a charger from a Playstation portable)

The floor switch is connected to the control box by a length of old VGA cable - it's nice and sturdy, and has more than enough wires for this project.

The components for the floor switch

In use
I finally managed to get a short video clip of Jack using it

Future improvements 

The floor switch is too light, as you can see in the video, when Jack uses it, he knocks it across the floor, so I've since mounted it to a bit of wood which helps hold it in place.

The small metal tin that I used to make the contact area larger & easier for Jack to use, ended up making the capacitive switch too sensitive - it basically became like a motion sensor - so I removed that, and used the original metal disc (about 15mm diameter) instead. Although the disc itself is smaller, it still manages to detect capacitance from contact anywhere on the switch, so it works just fine.

The floor switch - unfortunately the hot glue made a bit of a mess, but it's all contained on the underside of the switch, and actually helps diffuse the light a bit.

Source Code (Arduino cores for ATTiny2313

int latchPin = 8;
int clockPin = 12;
int dataPin = 11;
int capBtn = 7;

int plusBtn = 3;
int minBtn = 4;

int enabledLight = 5;

int motorPin = 6;

int treatCount = 0;
int valToDisplay = 0;
int timerBypassPin = 9;
long myTime;
boolean treatEnabled = false;

void setup() {
  //set pins to output so you can control the shift register
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  pinMode(capBtn, INPUT);
  pinMode(enabledLight, OUTPUT);
  pinMode(motorPin, OUTPUT);
  pinMode(plusBtn, INPUT);
  pinMode(minBtn, INPUT);
  pinMode(timerBypassPin, INPUT);
  digitalWrite(motorPin, LOW);
  digitalWrite(enabledLight, LOW);
  treatCount = 3;
}

void loop() {
  if (digitalRead(plusBtn) == HIGH) {
    treatCount++;
    if (treatCount > 8) { treatCount = 8; }
    delay(500);
  }
  
  if (digitalRead(minBtn) == HIGH) {
    treatCount--;
    if (treatCount < 0) { treatCount = 0; }
      delay(500);
  }
  
  if (digitalRead(timerBypassPin) == HIGH) {
    treatEnabled = true;
  }
  
  if (
      ((millis() - myTime) < 0) ||
      ((millis()-myTime) >= 3600000)
     ) {
    myTime = millis();
    treatEnabled = true;
  }
  digitalWrite(enabledLight, treatEnabled);

  if (digitalRead(capBtn) == HIGH) {
    if (treatEnabled) {
        digitalWrite(enabledLight, LOW);
        treatEnabled = false;
        treatCount--;
        digitalWrite(motorPin, HIGH);
        delay(3000);
        digitalWrite(motorPin, LOW);
    }
  }
  

  switch (treatCount) {
    case 0: valToDisplay = 0; break;
    case 1: valToDisplay = 1; break;
    case 2: valToDisplay = 3; break;
    case 3: valToDisplay = 7; break;
    case 4: valToDisplay = 15; break;
    case 5: valToDisplay = 31; break;
    case 6: valToDisplay = 63; break;
    case 7: valToDisplay = 127; break;
    case 8: valToDisplay = 255; break;
  }


  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, valToDisplay);
  digitalWrite(latchPin, HIGH);
  
}

Dog-controlled treat dispenser

I picked up one of these treat dispensers from Maplins on a whim - one of those "I'm-sure-I'll-find-a-use-for-this-someday" things. Subsequently I started wondering if I could train my dog, Jack, to use it (with some modifications, obviously)

An initial attempt involved simply wiring a switch to a footpedal for Jack to step on. That lasted all of 10 seconds as the plastic lid I'd repurposed as a pedal cracked under his weight.

One of the things that attracted me to the gadget in the first place was the capacitive button that it used. A quick test with my phone screen showed that dog's paws can operate capacitive switches.

Simply extending the leads alone wouldn't be enough. Although I want to give Jack the freedom to get his own treats, I still want to keep control over how many!

The touch sensors board has simple connections - just power, and leads out to the motor. I didn't really want to waste time modifying the board, as it's all small surface-mount components. Since I know the motor was only driven one direction by the board, I simply connected an optocoupler to the motor outputs. A couple of pull-up resistors later and the switch was done.

The finished capacitive button PCB with optocoupler

I connected a metal lid in place of the small capacitive disc to make it more dog-friendly.

Now onto the human's control system..

My original plan was to use something web connected such as an old android device, so that I could give Jack treats whilst out at work, but in practice, it was totally overkill, so I opted for a microcontroller based system instead.

The only controls I really need are to limit the number of available treats, set a time limit so he doesn't eat them all at once, and a way to see how many were available.

I found an old PCB with two buttons on it in my junk box. One button to add a treat, one to remove.

 

The salvaged button PCB (I believe it once belonged to a toaster...)

For a display I went with a 10-segment LED, controlled by a shift register. Due to the limitations of the shift register, the maximum treats available at any one time is 8 - which is more than enough anyway. The remaining 2 LEDs are left unused.

The 10 segment display (3 treats available) - the bottom 2 LEDs are not used.

The time limit I chose to fix at 1 hour in the microcontroller. As it's impossible to precisely measure the amount of treats that will be dispensed, the motor was set to a 3 second interval.

Finally I added a small LED module to the pedal, that lights when the timer ticks down and a treat is available, so that Jack could see when he can get a treat. According to the Pavlovian theory, he should soon learn that light=treat.

The LED module (it's just from one of those battery operated 'cupboard lights' you see in nearly every pound shop) - for this project I just connected a jumper over the button.

As with other projects I opted for using an Attiny (in this case the 2313) with the Attiny arduino cores, as they make it nice and easy to prototype with Arduino and switch to a regular AVR for the end product.

Stay tuned for part 2 - building an enclosure for it, some pictures of the completed project, source code, and hopefully some pictures/video of Jack using it.

UPDATE - Part 2 is now available here.