Automatic Kibble Dispenser

Do you have a pet? Or do you want one? Everyone loves pets, for some it's more dogs, for others it's cats. However, owning a pet involves a number of responsibilities. Fortunately, most of us take very good care of them, but that doesn't mean we don't want to go away for the weekend and leave our cat alone for a day or two, for example. But nobody wants to leave their cat without food. So some people fill several bowls in the hope that the cats will manage the distribution of food correctly over 2 days. Unfortunately, this is rarely the case. I myself have 2 cats: Oslo and Misty, and I can assure you that they are particularly greedy. That's what prompted me to develop this adjustable automatic kibble dispenser.

I invite you to follow my Instructable, so that you can reproduce this project, which is very close to my heart.

Materials required to create it:

• A 3D printer
• Wood and cutting materials
• Screws and bolts
• A screwdriver
• An empty 8L bottle, in my case a Volvic
• Pet bowls
• PVC tubes
• A soldering iron

Hardware required for programming:

• An ESP32, to buy click here
• A 5V Relay, to buy click here
• A 2N2907 transistor, to buy click here
• A 12V DC motor 36rpm, with brackets, to buy click here
• HX711 scale, to buy click here
• PCB Prototyping Board Hardware, to buy click here
• Cables
• A computer

We'll start by looking at the mechanical aspects of our distributor. It operates mainly through the rotation of a worm screw, which is driven by a motor. This is why the first step is to print all the parts of the dispenser in PLA. Personally, I printed the whole thing with 20% fill. I'd also advise you to print with tree-shaped supports, to make it easier for you when you have to remove the supports, particularly around the worm screw.

WARNING : Print the 'PipeConnector' only if you want to distribute to 2 cats/dogs. Print twice the 'Bracket'.

For the creation of the wooden structure, which is supposed to enclose the system, I think you'll probably have to adapt it according to your own constraints. For example, if you want the system to be lower for the bowls and so on.

However, I'll leave you with a sketch of my wooden structure from which you can draw inspiration.

Once you have the mechanical part of your system and the wooden structure, you can assemble the whole thing. To do this, place your bottle in the dedicated space, along with your 3D printed parts, as shown in the photo and in the sketch.

You can then mark out the markings and screw your parts onto the wooden board one by one. Avoid leaving too much play in the screw, as it could slip and no longer be in contact with the motor gear ('SmallestGear').

Then stick the worm gear to its start and the guide to the base using an adhesive such as ultraglue.

There are also 2 parts that need to be screwed to the load cell: ‘LoadCellBase’ and ‘TopPlate’. And then you can place the scales under one of the bowls.

To avoid any risk of false contact and to improve organisation, it is preferable to place our components on a PCB. We'll put ports for the scale and motor cables, as they're a little further apart. Please see the diagram.

To carry out this project, we'll need Visual Studio Code. For those of you who don't already have it, you can download and install it here.

In the extensions tab install PlatformIO and configure it for your ESP32-WROOM

The first thing to do is to calibrate your scales. To do this, you need to install the ‘HX711_ADC’ library and run the ‘Calibration’ example.

To be on the safe side, I advise you to create a new gmail address. Then, to make access to your account more secure, we're going to create an application that will generate a 16-character code for you to copy into the program.

Don't forget to replace certain variables with your own information and to install the missing libraries.

#include <WiFi.h>
#include <WebServer.h>
#include <HX711_ADC.h> //to install for the scale
#include <ESP_Mail_Client.h> //to install to send e-mail
#include <NTPClient.h> //to install to get the local time
#include <WiFiUdp.h>


#include <stdio.h>
#include <string.h>
#include <stdlib.h>


#define SMTP_server "smtp.gmail.com"
#define SMTP_Port 465
#define sender_email "email-created-for-esp32@gmail.com" //change with your informations
#define sender_password "****************" //change with your informations
#define Recipient_email "your-mail@gmail.com" //change with your informations
#define Recipient_name ""
SMTPSession smtp;


const char *ssid = "your_ssid"; //change with your informations
const char *password = "your_wifi_password"; //change with your informations
WebServer server(80);


const int led = 2;


int weight;
int minweight =  15;


const int HX711_dout = 4; 
const int HX711_sck = 5; 


HX711_ADC LoadCell(HX711_dout, HX711_sck);
const int calVal_eepromAdress = 0;
unsigned long t = 0;


WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP, "europe.pool.ntp.org", 7200, 60000); //change 7200 according to your time zone --> e.g. if you're UTC+2, it will be 3600*2


char time1[6] = "6:30";
char time2[6] = "12:30";
char time3[6] = "18:30";


const int mot = 23;


void handleRoot()
{
    String page = "<!DOCTYPE html>"; //we create a web page here to configure the distributor


    page += "<html lang='fr'>";


    page += "<head>";
    page += "    <title>Server ESP32</title>";
    page += "    <meta http-equiv='refresh' content='60' name='viewport' content='width=device-width, initial-scale=1' charset='UTF-8' />";
    page += "    <link rel='stylesheet' href='https://www.w3schools.com/w3css/4/w3.css'>";
    page += "</head>";


    page += "<body>";
    page += "    <div class='w3-card w3-blue w3-padding-small w3-jumbo w3-center'>";
    page += "        <p>Distributor configuration:</p>";
    page += "    </div>";


    page += "    <div class='w3-bar'>";
    page += "        <h4 style='text-align:left;font-size:70px;margin:20px;'>First distribution:</h4>";
    page += "        <h4 style='text-align:center;font-size:90px;'>"; page+= time1; +"</h4>";
    page += "        <a href='/time1sub' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:left;'>-</a>";"";
    page += "        <a href='/time1add' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:right;'>+</a>";"</br></div>";


    page += "    <div class='w3-bar'>";
    page += "        <h4 style='text-align:left;font-size:70px;margin:20px;'>Second distribution:</h4>";
    page += "        <h4 style='text-align:center;font-size:90px;'>"; page+= time2; +"</h4>";
    page += "        <a href='/time2sub' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:left;'>-</a>";"";
    page += "        <a href='/time2add' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:right;'>+</a>";"</br></div>";


    page += "    <div class='w3-bar'>";
    page += "        <h4 style='text-align:left;font-size:70px;margin:20px;'>Third distribution:</h4>";
    page += "        <h4 style='text-align:center;font-size:90px;'>"; page+= time3; +"</h4>";
    page += "        <a href='/time3sub' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:left;'>-</a>";"";
    page += "        <a href='/time3add' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:right;'>+</a>";"</br></div>";
    
    page += "    <div class='w3-bar'>";
    page += "        <h4 style='text-align:left;font-size:70px;margin:20px;'>Kibble mass per feed (in g):</h4>";
    page += "        <h4 style='text-align:center;font-size:80px;'>"; page+= String(minweight); +"</h4>";
    page += "        <a href='/minweightsub' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:left;'>-</a>";"";
    page += "        <a href='/minweightadd' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%; float:right;'>+</a>";"</br></div>";


    page += "    <div class='w3-bar'>";
    page += "        <h4 style='text-align:left;font-size:70px;margin:20px;'>Ration supplémentaire :</h4>";
    page += "        <a href='/bonus' class='w3-bar-item w3-button w3-border w3-jumbo' style='width:30%; height:30%;margin-left:35%;;border-radius:50px;'>BONUS !</a>";"</br></div>";
    
    page += "</body>";


    page += "</html>";


    server.setContentLength(page.length());
    server.send(200, "text/html", page);
}


//Defined voids are used to modify variables such as distribution times and distributed mass


void time1addvoid()
{    
    int hours = atoi(strtok((char *)time1, ":"));
    int minutes = atoi(strtok(NULL, ":"));


    minutes += 5;
    
    if (minutes >= 60) {
        hours += minutes / 60;
        minutes %= 60;
    }
    sprintf(time1, "%02d:%02d", hours, minutes);


    Serial.println(time1);


    server.sendHeader("Location","/");
    server.send(303);
    
}


void time1subvoid()
{
    int hours = atoi(strtok((char *)time1, ":"));
    int minutes = atoi(strtok(NULL, ":"));


    minutes -= 5;


    if (minutes < 0) {
    hours -= 1;
    minutes = 55;
    }


    sprintf(time1, "%02d:%02d", hours, minutes);
    Serial.println(time1);


    server.sendHeader("Location","/");
    server.send(303);
}


void time2addvoid()
{    
    int hours = atoi(strtok((char *)time2, ":"));
    int minutes = atoi(strtok(NULL, ":"));


    minutes += 5;


    if (minutes >= 60) {
        hours += minutes / 60;
        minutes %= 60;
    }
    sprintf(time2, "%02d:%02d", hours, minutes);


    Serial.println(time2);


    server.sendHeader("Location","/");
    server.send(303);
    
}


void time2subvoid()
{
    int hours = atoi(strtok((char *)time2, ":"));
    int minutes = atoi(strtok(NULL, ":"));


    minutes -= 5;


    if (minutes < 0) {
    hours -= 1;
    minutes = 55;
    }


    sprintf(time2, "%02d:%02d", hours, minutes);
    Serial.println(time2);


    server.sendHeader("Location","/");
    server.send(303);
}


void time3addvoid()
{    
    int hours = atoi(strtok((char *)time3, ":"));
    int minutes = atoi(strtok(NULL, ":"));


    minutes += 5;


    if (minutes >= 60) {
        hours += minutes / 60;
        minutes %= 60;
    }
    sprintf(time3, "%02d:%02d", hours, minutes);


    Serial.println(time3);


    server.sendHeader("Location","/");
    server.send(303);
    
}


void time3subvoid()
{
    int hours = atoi(strtok((char *)time3, ":"));
    int minutes = atoi(strtok(NULL, ":"));


    minutes -= 5;


    if (minutes < 0) {
    hours -= 1;
    minutes = 55;
    }


    sprintf(time3, "%02d:%02d", hours, minutes);
    Serial.println(time3);


    server.sendHeader("Location","/");
    server.send(303);
}


void minweightaddvoid()
{
    minweight += 1;
    server.sendHeader("Location","/");
    server.send(303);
}


void minweightsubvoid()
{
    minweight -= 1;
    server.sendHeader("Location","/");
    server.send(303);
}


/ / Sometimes our animal friends are well-behaved and we want to please them, so I've created a Bonus void that delivers a few extra kibbles immediately.


void bonusvoid()
{
    digitalWrite(mot, HIGH);
    delay(5000);
    digitalWrite(mot, LOW);


    server.sendHeader("Location","/");
    server.send(303);
}


void handleNotFound()
{
    server.send(404, "text/plain", "404: Not found");
}


//If there's an error, it will call this void
void errordistrib()
{
    ESP_Mail_Session session;
    session.server.host_name = SMTP_server ;
    session.server.port = SMTP_Port;
    session.login.email = sender_email;
    session.login.password = sender_password;
    session.login.user_domain = "";


    SMTP_Message message;
    message.sender.name = "Kibble dispenser - ALERTS";
    message.sender.email = sender_email;
    message.subject = "ERROR - DISTRIBUTION";
    message.addRecipient(Recipient_name,Recipient_email);


    String textMsg = "Unfortunately, the kibble dispenser doesn't seem to have worked!";


    message.text.content = textMsg.c_str();


    message.text.charSet = "us-ascii";


    message.text.transfer_encoding = Content_Transfer_Encoding::enc_7bit;


    if (!smtp.connect(&session))


        return;


    if (!MailClient.sendMail(&smtp, &message))


        Serial.println("Error sending Email");
}


//void which measures the quantity of kibble
void weightmeasurement()
{
    static boolean newDataReady = 0;
    const int serialPrintInterval = 0; 


    // check for new data/start next conversion:
    if (LoadCell.update()) newDataReady = true;


    // get smoothed value from the dataset:
    if (newDataReady) {
        if (millis() > t + serialPrintInterval) {
        weight = LoadCell.getData();
        Serial.print("Load_cell output val: ");
        Serial.println(weight);
        newDataReady = 0;
        t = millis();
        }
    }


    Serial.println("Weight : " + char(weight));
}


void setup()
{


    //Initialization of the motor
    pinMode(mot, OUTPUT);


    //Initialization serial monitor
    Serial.begin(115200); delay(10);
    Serial.println();
    Serial.println("Starting...");
    
    //Initalization LED
    pinMode(led, OUTPUT);
    digitalWrite(led, LOW);


    //Connection attempt
    WiFi.persistent(false);
    WiFi.begin(ssid, password);
    Serial.print("Tentative de connexion...");


    while (WiFi.status() != WL_CONNECTED)
    {
        Serial.print(".");
        delay(100);
    }


    Serial.println("\n");
    Serial.println("Connexion etablie!");
    Serial.print("Adresse IP: ");
    Serial.println(WiFi.localIP());


    //Define voids for each request
    server.on("/", handleRoot);
    server.on("/time1add", time1addvoid);
    server.on("/time1sub", time1subvoid);
    server.on("/time2add", time2addvoid);
    server.on("/time2sub", time2subvoid);
    server.on("/time3add", time3addvoid);
    server.on("/time3sub", time3subvoid);
    server.on("/minweightadd", minweightaddvoid);
    server.on("/minweightsub", minweightsubvoid);
    server.on("/bonus", bonusvoid);
    server.onNotFound(handleNotFound);
    server.begin();


    Serial.println("Active web server!");
    digitalWrite(led, HIGH);


    //Starting the local time function
    
    timeClient.begin();


    //Sending of an e-mail to confirm successful start-up
    ESP_Mail_Session session;
    session.server.host_name = SMTP_server ;
    session.server.port = SMTP_Port;
    session.login.email = sender_email;
    session.login.password = sender_password;
    session.login.user_domain = "";


    SMTP_Message message;
    message.sender.name = "Kibble dispenser - INITALIZATION";
    message.sender.email = sender_email;
    message.subject = "ESP32 Testing Email";
    message.addRecipient(Recipient_name,Recipient_email);


    String textMsg = "The kibble dispenser has been switched on correctly.";


    message.text.content = textMsg.c_str();


    message.text.charSet = "us-ascii";


    message.text.transfer_encoding = Content_Transfer_Encoding::enc_7bit;


    if (!smtp.connect(&session))
        return;


    if (!MailClient.sendMail(&smtp, &message))
        Serial.println("Error sending Email");
}


void loop()
{
    server.handleClient();
    
    timeClient.update();
    String currenttime = timeClient.getFormattedTime();
    currenttime = currenttime.substring(0, 5);


    if(currenttime == String(time1) || currenttime == String(time2) || currenttime == String(time3)){
        float chrono = 0;
        LoadCell.begin();
        float calibrationValue; 
        calibrationValue = -1040.0; 
        unsigned long stabilizingtime = 2000;
        boolean _tare = true; 
        LoadCell.start(stabilizingtime, _tare);
        if (LoadCell.getTareTimeoutFlag()) {
            Serial.println("Timeout, check MCU>HX711 wiring and pin designations");
            while (1);
        }
        else {
            LoadCell.setCalFactor(calibrationValue); // set calibration value (float)
            Serial.println("Startup is complete");
        }
        while(weight <= minweight){
            digitalWrite(mot, HIGH);
            delay(500);
            chrono += 0.5;
            weightmeasurement();
            if(chrono>=20){
                erreurdistrib();
                break;
            }
        }
        digitalWrite(mot, LOW);
        delay(60000);
    }


    
}

Use your adress IP to control it. After many trials, Oslo and Misty can assure you that it works well and that they are delighted with it.

I hope you enjoy it! Don't hesitate to leave comments! And I just wanted to add a clarification, because you probably noticed on the photos, that there was a lot of tape, because my cats love to jump on it. That's why I'm probably going to put some extra protection on it to hide the mechanical and electronic parts.