ESP 32 Project

Temperature Difference Calculation in MicroPython for ESP32 and ESP8266

In this project, we will read two temperature values from a sensor (such as the DHT11 or DHT22) and calculate the temperature difference between them. This project demonstrates how to use subtraction and division operators to calculate and display the difference. By performing simple arithmetic operations on sensor data, you’ll gain a practical understanding of how to work with Temperature Difference Calculation in MicroPython for ESP32 and ESP8266.

Data Types and Variable Table for Temperature Difference Calculation:

Data Type Variable Name Description Example Value
Float temp1 Stores the first temperature reading 25.0°C
Float temp2 Stores the second temperature reading 30.5°C
Float temp_difference Stores the difference between the two values 5.5°C

In this project, temperature values are read as floating-point numbers and used to calculate their difference.

Syntax Table for Temperature Difference Calculation in MicroPython:

Operation Syntax Example
Subtraction temp_difference = temp1 – temp2 temp_difference = 30.5 – 25.0
Division (optional) average_temp = (temp1 + temp2) / 2 average_temp = (25.0 + 30.5) / 2

This table outlines the key operations used in this project, focusing on subtraction and division for temperature calculations.

Required Components:

  • ESP32 or ESP8266
  • DHT11 or DHT22 Sensor (Temperature and humidity sensor)
  • Jumper wires
  • Breadboard

These components will allow you to read temperature data and perform calculations on it.

Circuit Diagram:

          DHT11/DHT22       ESP32/ESP8266

           ————      ————

           VCC  ———->  3.3V

           GND  ———->  GND

           DATA ———->  GPIO4 (Pin 4)

 

Circuit Connection Table:

Component Connection ESP32/ESP8266 Pin Explanation
DHT11/DHT22 Pin VCC (Power) 3.3V on ESP32/ESP8266 Supplies power to the DHT11/DHT22 sensor.
DHT11/DHT22 Pin GND (Ground) GND on ESP32/ESP8266 Connects the sensor to ground.
DHT11/DHT22 Pin DATA (Data line) GPIO4 on ESP32/ESP8266 Sends temperature data to the microcontroller.

Warnings:

  • Ensure the sensor is connected to the 3.3V pin of the ESP32/ESP8266 to avoid damaging the sensor.
  • Always check wiring before powering the circuit to prevent connection issues.

Installing MicroPython and Libraries:

Install MicroPython on ESP32/ESP8266: If you haven’t already installed MicroPython on your ESP32 or ESP8266, follow these steps:
esptool.py –chip esp32 erase_flash

esptool.py –chip esp32 write_flash -z 0x1000 esp32-20210902-v1.17.bin

Install Required Libraries: To read data from the DHT11 or DHT22 sensor, you’ll need to import the dht module:
import dht

import machine

import time

Writing the MicroPython Code for Temperature Difference Calculation:

Here’s the code to read temperature values from the DHT11 sensor, calculate the difference, and display the result:

import dht

import machine

import time

 

# Initialize the DHT sensor (DHT11 or DHT22)

sensor = dht.DHT11(machine.Pin(4))  # Use DHT22 for DHT22 sensor

 

def read_temperature():

    # Trigger the sensor to measure temperature

    sensor.measure()

    # Return the temperature reading as a float

    return float(sensor.temperature())

 

# Read two temperature values

print(“Reading first temperature…”)

temp1 = read_temperature()

time.sleep(2)

 

print(“Reading second temperature…”)

temp2 = read_temperature()

 

# Calculate the temperature difference

temp_difference = temp2 – temp1

print(“Temperature 1:”, temp1, “°C”)

print(“Temperature 2:”, temp2, “°C”)

print(“Temperature difference:”, temp_difference, “°C”)

 

# Optional: Calculate the average temperature

average_temp = (temp1 + temp2) / 2

print(“Average temperature:”, average_temp, “°C”)

 

Explanation of the Code:

  1. The read_temperature() function reads the temperature from the DHT sensor and converts it to a float.
  2. The program reads two temperature values, temp1 and temp2, with a 2-second delay in between.
  3. The temperature difference is calculated by subtracting temp1 from temp2.
  4. The result is printed along with the individual temperatures.
  5. Optionally, the code calculates and prints the average temperature using the division operator.

Running the Code and Checking the Output:

  1. Upload the code to your ESP32/ESP8266 using Thonny or another MicroPython IDE.

Observe the output on the serial monitor, which will display the two temperature values, their difference, and the average temperature:
Reading first temperature…

Temperature 1: 25.0 °C

Reading second temperature…

Temperature 2: 30.5 °C

Temperature difference: 5.5 °C

Average temperature: 27.75 °C

Expanding the Project:

  • Multiple Sensor Readings: Expand the project to read more than two temperature values and calculate the difference between multiple readings.
  • Add an OLED Display: Display the temperature values and their difference on an OLED screen instead of the serial monitor.
  • Log Data: Store temperature readings and their differences in a file for later analysis.

Common Problems and Solutions:

  1. Problem: Incorrect temperature readings or no data output.
    • Solution: Check the wiring, especially the DATA pin. Ensure the correct GPIO pin is used in the code.
  2. Problem: Sensor is not responding or giving an error.
    • Solution: Ensure the sensor is powered correctly and connected to the right pin. Also, verify the integrity of the sensor.
  3. Problem: Incorrect temperature difference calculation.
    • Solution: Double-check the order of subtraction (e.g., temp2 – temp1) to ensure the difference is calculated correctly.

FAQ:

Q: Can I use a different GPIO pin for the sensor?
A: Yes, you can connect the sensor’s DATA pin to any available GPIO pin on the ESP32/ESP8266. Be sure to update the pin number in the code accordingly.

Q: How do I handle sensor errors?
A: Use try-except blocks to handle potential sensor errors and avoid program crashes.

Q: Can I use a different sensor like DHT22?
A: Yes, simply change the sensor initialization from dht.DHT11() to dht.DHT22() in the code.

Conclusion:

In this project, you successfully built a program to calculate the temperature difference between two readings using MicroPython for ESP32 and ESP8266. By utilizing subtraction and division operators, you learned how to process sensor data and perform basic calculations. This project can be expanded by adding displays, logging data, or even connecting multiple sensors for advanced temperature monitoring.

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