PIR Sensor for Fish Tank Feeding Reminder

Project Overview

This project creates a smart feeding reminder for your aquarium. When you approach the fish tank, the system checks if it is time to feed and plays a voice reminder if needed. It also tracks the last feeding time and prevents overfeeding.

Difficulty: Beginner
Estimated time: 1-2 hours
Estimated cost: $20-30

How It Works

A PIR sensor detects when someone approaches the fish tank. The ESP32 checks the current time against a feeding schedule. If it is within the feeding window and the last feeding was more than 8 hours ago, it plays a voice reminder. A button can be pressed to mark feeding as done.

Materials Needed

• ESP32 (1)
• HC-SR501 PIR sensor (1)
• DFPlayer Mini MP3 module (1)
• MicroSD card with feeding reminder audio
• Small speaker (3W)
• Push button to mark feeding done
• LEDs for status (optional)
• 220Ω resistors
• Jumper wires
• Power supply (5V 1A)

Circuit Diagram

Connection Table

OUT

GPIO 4

–

GPIO 16

–

GPIO 17

One side

GPIO 5

Anode

GPIO 2

Anode

GPIO 15

表

Arduino Code

// Fish Tank Feeding Reminder
#include <WiFi.h>
#include <SoftwareSerial.h>
#include <DFRobotDFPlayerMini.h>
#include <time.h>

SoftwareSerial mySoftwareSerial(16, 17);
DFRobotDFPlayerMini myDFPlayer;

const int pirPin = 4;
const int buttonPin = 5;
const int greenLedPin = 2;
const int redLedPin = 15;

const char* ntpServer = "pool.ntp.org";
const long gmtOffset = 0;
const int daylightOffset = 0;

struct FeedingTime {
  int hour;
  int minute;
};

FeedingTime feedTimes[] = {{8, 0}, {18, 0}};
const int numFeedTimes = 2;

unsigned long lastFeedTime = 0;
bool fedToday[2] = {false, false};
unsigned long lastReminderTime = 0;
const unsigned long reminderCooldown = 3600000;

void setup() {
  Serial.begin(115200);
  
  pinMode(pirPin, INPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(greenLedPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);
  
  digitalWrite(greenLedPin, LOW);
  digitalWrite(redLedPin, LOW);
  
  WiFi.begin("YourSSID", "YourPassword");
  while (WiFi.status() != WL_CONNECTED) delay(500);
  configTime(gmtOffset, daylightOffset, ntpServer);
  
  mySoftwareSerial.begin(9600);
  myDFPlayer.begin(mySoftwareSerial);
  myDFPlayer.volume(20);
  
  delay(30000);
}

bool isTimeToFeed(int currentHour, int currentMinute, int feedHour, int feedMinute) {
  int currentMinutes = currentHour * 60 + currentMinute;
  int feedMinutes = feedHour * 60 + feedMinute;
  return (currentMinutes >= feedMinutes && currentMinutes < feedMinutes + 30);
}

void markFed(int feedIndex) {
  fedToday[feedIndex] = true;
  lastFeedTime = millis();
  digitalWrite(greenLedPin, HIGH);
  myDFPlayer.play(3);
  delay(2000);
  digitalWrite(greenLedPin, LOW);
}

void playReminder(int feedIndex) {
  myDFPlayer.play(feedIndex == 0 ? 1 : 2);
  digitalWrite(redLedPin, HIGH);
  delay(2000);
  digitalWrite(redLedPin, LOW);
}

void resetDaily() {
  struct tm timeinfo;
  if (getLocalTime(&timeinfo)) {
    if (timeinfo.tm_hour == 0 && timeinfo.tm_min == 0) {
      for (int i = 0; i < numFeedTimes; i++) fedToday[i] = false;
    }
  }
}

void loop() {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) return;
  
  resetDaily();
  
  bool motion = digitalRead(pirPin) == HIGH;
  bool buttonPressed = digitalRead(buttonPin) == LOW;
  
  if (buttonPressed) {
    delay(50);
    if (digitalRead(buttonPin) == LOW) {
      for (int i = 0; i < numFeedTimes; i++) {
        if (isTimeToFeed(timeinfo.tm_hour, timeinfo.tm_min, feedTimes[i].hour, feedTimes[i].minute)) {
          markFed(i);
          break;
        }
      }
      while (digitalRead(buttonPin) == LOW) delay(10);
    }
  }
  
  if (motion && (millis() - lastReminderTime > reminderCooldown)) {
    for (int i = 0; i < numFeedTimes; i++) {
      if (isTimeToFeed(timeinfo.tm_hour, timeinfo.tm_min, feedTimes[i].hour, feedTimes[i].minute) && !fedToday[i]) {
        lastReminderTime = millis();
        playReminder(i);
        break;
      }
    }
  }
  
  delay(100);
}

Installation Steps

1. Mount PIR sensor near fish tank
2. Position speaker where reminder can be heard clearly
3. Mount button near fish tank for easy access after feeding
4. Assemble electronics in small box
5. Adjust feeding times in code to match your schedule
6. Approach tank at feeding time to test reminder

Project Extensions

• Add servo to dispense food automatically
• Add Wi-Fi dashboard to view feeding history
• Add mobile notifications when feeding is missed
• Add DS18B20 to monitor tank temperature
• Add LED strip to simulate sunrise/sunset

Conclusion

This fish tank feeding reminder ensures your aquatic pets are fed on schedule with voice reminders.