Circuit Documentation

Summary

This circuit is a health monitoring system that uses an ESP8266 NodeMCU and an Arduino Uno R3 to monitor a patient's presence on a bed using an IR sensor. The system also includes a heart rate monitor, a relay to control a DC motor, and a buzzer for alerts. The status is displayed on a 16x2 I2C LCD.

Component List

1. ESP8266 NodeMCU

   • Description: A low-cost Wi-Fi microcontroller.
   • Pins: D0, D1, D2, D3, D4, 3V3, GND, D5, D6, D7, D8, RX, TX, A0, RSV, SD3, SD2, SD1, CMD, SD0, CLK, EN, RST, VIN

2. 1 Channel Relay 5V

   • Description: A relay module to control high voltage devices.
   • Pins: VCC, GND, IN, NC, COM, NO

3. AD8232 Heart Rate Monitor

   • Description: A heart rate monitor sensor.
   • Pins: GND, 3.3v, OUTPUT, LO-, LO+, SDN, RA, LA, RL

4. IR Sensor

   • Description: An infrared sensor to detect presence.
   • Pins: out, gnd, vcc

5. Buzzer

   • Description: A simple buzzer for audio alerts.
   • Pins: GND, IN

6. 16x2 I2C LCD

   • Description: A 16x2 character LCD with I2C interface.
   • Pins: GND, VCC, SDA, SCL

7. Arduino Uno R3

   • Description: A popular microcontroller board.
   • Pins: D8, D9, D10, D11, D12, D13, GND, AREF, SDA, SCL, D0/RX, D1/Tx, D2, D3, D4, D5, 6, D7, A5/SCL, A4/SDA, A3, A2, A1, A0, Vin, 5V, 3.3V, RESET, IOREF, NONE, USB Jack, Power Jack

8. Battery 18650

   • Description: A rechargeable lithium-ion battery.
   • Pins: +, -

9. LED: Two Pin (yellow)

   • Description: A yellow LED.
   • Pins: cathode, anode

10. Resistor

    • Description: A resistor with various resistance values.
    • Pins: pin1, pin2
    • Properties: 1000 Ohms, 2000 Ohms, 3000 Ohms

11. DC Motor

    • Description: A simple DC motor.
    • Pins: pin 1, pin 2

12. Rocker Switch

    • Description: A simple on/off switch.
    • Pins: output, input

Wiring Details

ESP8266 NodeMCU

• GND: Connected to the cathode of all yellow LEDs and the GND of the heart rate monitor and relay.
• D1: Connected to pin2 of three 1000 Ohm resistors.
• D2: Connected to the IN pin of the relay.
• RX: Connected to D0/RX of the Arduino Uno.
• TX: Connected to pin2 of a 2000 Ohm resistor.
• 3V3: Connected to the VCC of the relay and the 3.3v of the heart rate monitor.
• A0: Connected to the OUTPUT of the heart rate monitor.

1 Channel Relay 5V

• IN: Connected to D2 of the ESP8266 NodeMCU.
• VCC: Connected to 3V3 of the ESP8266 NodeMCU.
• GND: Connected to GND of the ESP8266 NodeMCU.
• COM: Connected to the positive terminal of the 18650 battery.
• NO: Connected to pin 1 of the DC motor.

AD8232 Heart Rate Monitor

• GND: Connected to GND of the ESP8266 NodeMCU.
• 3.3v: Connected to 3V3 of the ESP8266 NodeMCU.
• OUTPUT: Connected to A0 of the ESP8266 NodeMCU.

IR Sensor

• out: Connected to D2 of the Arduino Uno.
• gnd: Connected to GND of the Arduino Uno.
• vcc: Connected to 5V of the Arduino Uno.

Buzzer

• GND: Connected to GND of the Arduino Uno.
• IN: Connected to the output of the rocker switch.

16x2 I2C LCD

• GND: Connected to GND of the Arduino Uno.
• VCC: Connected to 5V of the Arduino Uno.
• SDA: Connected to A4/SDA of the Arduino Uno.
• SCL: Connected to A5/SCL of the Arduino Uno.

Arduino Uno R3

• D0/RX: Connected to RX of the ESP8266 NodeMCU.
• D1/Tx: Connected to pin2 of a 2000 Ohm resistor.
• D2: Connected to the out pin of the IR sensor.
• D3: Connected to the input of the rocker switch.
• GND: Connected to GND of the IR sensor, LCD, and buzzer.
• 5V: Connected to vcc of the IR sensor and LCD.
• A4/SDA: Connected to SDA of the LCD.
• A5/SCL: Connected to SCL of the LCD.

Battery 18650

• +: Connected to COM of the relay.
• -: Connected to pin 2 of the DC motor.

LED: Two Pin (yellow)

• cathode: Connected to GND of the ESP8266 NodeMCU.
• anode: Connected to pin1 of 1000 Ohm resistors.

Resistor

• pin1: Connected to the anode of yellow LEDs.
• pin2: Connected to D1 of the ESP8266 NodeMCU and D1/Tx of the Arduino Uno.

DC Motor

• pin 1: Connected to NO of the relay.
• pin 2: Connected to the negative terminal of the 18650 battery.

Rocker Switch

• output: Connected to IN of the buzzer.
• input: Connected to D3 of the Arduino Uno.

Documented Code

ESP8266 NodeMCU Code

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

Arduino Uno R3 Code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Initialize the LCD with I2C address 0x27 and dimensions 16x2
LiquidCrystal_I2C lcd(0x27, 16, 2);

#define IR_PIN 2       // IR sensor input pin
#define BUZZER_PIN 3   // Buzzer output pin

void setup() {
  // Initialize the LCD
  lcd.begin();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Health Monitor");

  // Initialize IR sensor and buzzer
  pinMode(IR_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  // Display initial status
  lcd.setCursor(0, 1);
  lcd.print("Initializing...");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read IR sensor status
  int irStatus = digitalRead(IR_PIN);

  // Adjusted logic for active-low sensors
  if (irStatus == LOW) { // Patient detected
    lcd.setCursor(0, 0);
    lcd.print("Patient on Bed   "); // Clear extra characters
    lcd.setCursor(0, 1);
    lcd.print("Status: Safe     ");
    digitalWrite(BUZZER_PIN, LOW); // Turn off buzzer
  } else { // Patient not detected
    lcd.setCursor(0, 0);
    lcd.print("Patient not on   ");
    lcd.setCursor(0, 1);
    lcd.print("Bed! Alert!      ");
    digitalWrite(BUZZER_PIN, HIGH); // Turn on buzzer
  }

  delay(500);
}