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Arduino and Raspberry Pi-Based Smart Temperature Control System with I2C LCD Display

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Circuit Documentation

Summary

This document provides a detailed overview of a circuit that includes various components such as resistors, thermistors (NTC), an I2C LCD screen, an Arduino UNO, a Raspberry Pi 4B, a battery, LED tactile button breakouts, relay modules, a Peltier module, a water pump, and a fan. The circuit is designed to interface with multiple sensors and actuators, controlled by microcontrollers (Arduino UNO and Raspberry Pi 4B). The document includes a component list, wiring details, and documented code for the microcontrollers.

Component List

Resistor

  • Description: A passive electrical component that implements electrical resistance as a circuit element.
  • Pins: pin1, pin2
  • Properties:
    • Resistance: 10,000 Ohms

Arduino UNO

  • Description: A microcontroller board based on the ATmega328P.
  • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

NTC (Negative Temperature Coefficient Thermistor)

  • Description: A type of resistor whose resistance decreases as the temperature increases.
  • Pins: A0, A1

I2C LCD 16x2 Screen

  • Description: A 16x2 character LCD display with I2C interface.
  • Pins: SCL, SDA, VCC (5V), GND, VDD, VO, RS, RW, E, D0, D1, D2, D3, D4, D5, D6, D7, BLA, BLK

Battery

  • Description: A device consisting of one or more electrochemical cells with external connections for powering electrical devices.
  • Pins: -, +

LED Tactile Button Breakout

  • Description: A breakout board for a tactile button with an integrated LED.
  • Pins: C, B1, B2, A

Relay Module 5V-30V

  • Description: A relay module that can be controlled with a voltage between 5V and 30V.
  • Pins: common contact, normally open, normally closed, trigger, V-, V+

Peltier Module

  • Description: A thermoelectric device that can heat or cool depending on the direction of the current.
  • Pins: Negative, Positive

Water Pump

  • Description: A device used to move liquids.
  • Pins: VCC, GND

Fan

  • Description: A device used to create airflow.
  • Pins: GND, 5V

Raspberry Pi 4B

  • Description: A small single-board computer.
  • Pins: 3V3, 5V, GPIO2, GPIO3, GND, GPIO4, GPIO14, GPIO15, GPIO17, GPIO18, GPIO27, GPIO22, GPIO23, GPIO24, GPIO10, GPIO9, GPIO25, GPIO11, GPIO8, GPIO7, ID_SD, GPIO5, GPIO6, GPIO12, GPIO13, GPIO19, GPIO16, GPIO26, GPIO20, GPIO21, ID_SC, TR01_TAP, TR00_TAP, TR03_TAP, TR02_TAP, RUN, GLOBAL_EN, ETH, HDMI 0, HDMI 1, CAMERA, AV

Wiring Details

Resistor

  • Resistor 1:

    • pin1: Connected to pin1 of another resistor, B2 of two LED tactile button breakouts, GND of Arduino UNO, GND of Raspberry Pi 4B, and - of a battery.
    • pin2: Connected to A1 of Arduino UNO and A0 of an NTC.

  • Resistor 2:

    • pin1: Connected to pin1 of another resistor, B2 of two LED tactile button breakouts, GND of Arduino UNO, GND of Raspberry Pi 4B, and - of a battery.
    • pin2: Connected to A0 of Arduino UNO and A0 of an NTC.

Arduino UNO

  • Arduino UNO 1:

    • 5V: Connected to VCC (5V) of I2C LCD screen, + of a battery, and 5V of Raspberry Pi 4B.
    • GND: Connected to pin1 of two resistors, B2 of two LED tactile button breakouts, and GND of Raspberry Pi 4B.
    • A1: Connected to pin2 of a resistor and A0 of an NTC.
    • A0: Connected to pin2 of a resistor and A0 of an NTC.
    • A4: Connected to GPIO2 of Raspberry Pi 4B.
    • A5: Connected to GPIO3 of Raspberry Pi 4B.
    • D8: Connected to B1 of an LED tactile button breakout.
    • D7: Connected to B1 of an LED tactile button breakout.
    • D6: Connected to trigger of a relay module.
    • D2: Connected to trigger of a relay module.

  • Arduino UNO 2:

    • 5V: Connected to V+ and common contact of a relay module.
    • GND: Connected to V- of three relay modules, B2 of an LED tactile button breakout, and - of a battery.
    • A4: Connected to GPIO2 of Raspberry Pi 4B.
    • A5: Connected to GPIO3 of Raspberry Pi 4B.
    • D8: Connected to trigger of a relay module.
    • D7: Connected to B1 of an LED tactile button breakout.

NTC

  • NTC 1:

    • A0: Connected to pin2 of a resistor and A1 of Arduino UNO.
    • A1: Connected to A1 of another NTC, VCC (5V) of I2C LCD screen, + of a battery, and 5V of Raspberry Pi 4B.

  • NTC 2:

    • A0: Connected to pin2 of a resistor and A0 of Arduino UNO.
    • A1: Connected to A1 of another NTC, VCC (5V) of I2C LCD screen, + of a battery, and 5V of Raspberry Pi 4B.

I2C LCD 16x2 Screen

  • VCC (5V): Connected to A1 of two NTCs, + of a battery, and 5V of Arduino UNO and Raspberry Pi 4B.
  • GND: Connected to GND of Arduino UNO.
  • SDA: Connected to A4 of Arduino UNO.
  • SCL: Connected to A5 of Arduino UNO.

Battery

  • +: Connected to VCC (5V) of I2C LCD screen, A1 of two NTCs, and 5V of Arduino UNO and Raspberry Pi 4B.
  • -: Connected to pin1 of two resistors, B2 of two LED tactile button breakouts, GND of Arduino UNO, and GND of Raspberry Pi 4B.

LED Tactile Button Breakout

  • LED Tactile Button Breakout 1:

    • B2: Connected to pin1 of two resistors, GND of Arduino UNO, and GND of Raspberry Pi 4B.
    • B1: Connected to D8 of Arduino UNO.

  • LED Tactile Button Breakout 2:

    • B2: Connected to pin1 of two resistors, GND of Arduino UNO, and GND of Raspberry Pi 4B.
    • B1: Connected to D7 of Arduino UNO.

  • LED Tactile Button Breakout 3:

    • B2: Connected to V- of three relay modules, GND of Arduino UNO, and - of a battery.
    • B1: Connected to D7 of Arduino UNO.

Relay Module 5V-30V

  • Relay Module 1:

    • V-: Connected to GND of Arduino UNO and - of a battery.
    • V+: Connected to 5V of Arduino UNO.
    • trigger: Connected to D6 of Arduino UNO.
    • common contact: Connected to V+ of the same relay module and + of a battery.
    • normally open: Connected to 5V of a fan.

  • Relay Module 2:

    • V-: Connected to GND of Arduino UNO and - of a battery.
    • V+: Connected to 5V of Arduino UNO.
    • trigger: Connected to D2 of Arduino UNO.
    • common contact: Connected to V+ of the same relay module and + of a battery.
    • normally open: Connected to VCC of a water pump.

  • Relay Module 3:

    • V-: Connected to GND of Arduino UNO and - of a battery.
    • V+: Connected to 5V of Arduino UNO.
    • trigger: Connected to D8 of Arduino UNO.
    • common contact: Connected to V+ of the same relay module and + of a battery.
    • normally open: Connected