HOW to Detect Temperature with ESP32

Description

In this kit, there is a DS18B20 temperature sensor, which is from maxim. The MCU can communicate with the DS18B20 through 1-Wire protocol, and finally read the temperature.

In this experiment, we will use this temperature sensor to measure the temperature in the current environment. The test result is ℃, ranging from -55℃ to +125℃. We will display the test result on shell.

Working Principle

The hardware interface of the 1-Wire bus is very simple, just connect the data pin of the DS18B20 to an IO port of the microcontroller. The timing of the 1-Wire bus is relatively complex. Many students can’t understand the timing diagram independently here. We have encapsulated the complex timing operations in the library, and you can use the library functions directly.

Schematic Diagram of DS18B20

This can save up to 12-bit temperature vale. In the register, save in code complement. As shown below;

A total of 2 bytes, LSB is the low byte, MSB is the high byte, where MSb is the high byte of the byte, LSb is the low byte of the byte. As you can see, the binary number, the meaning of the temperature represented by each bit, is expressed. Among them, S represents the sign bit, and the lower 11 bits are all powers of 2, which are used to represent the final temperature. The temperature measurement range of DS18B20 is from -55 degrees to +125 degrees, and the expression form of temperature data, S represents positive and negative temperature, and the resolution is 2﹣⒋, which is 0.0625.

Required Components

Required Components

Test Code

//**********************************************************************************
/*  
 * Description : Read the temperature of ds18B20
 * Auther      : http//www.keyestudio.com
*/
#include <DS18B20.h>

//ds18b20 pin to 15
DS18B20 ds18b20(15);

void setup() {
  Serial.begin(9600);
}

void loop() {
  double temp = ds18b20.GetTemp();//Read the temperature
  temp *= 0.0625;//The conversion accuracy is 0.0625/LSB
  Serial.print("Temperature: ");
  Serial.print(temp);
  Serial.println("C");
  delay(1000);
}
//**********************************************************************************

Code Explanation

We set the pin to GPIO15 and obtain the temperature in the unit of ℃.

Set a double decimal variable to temp, and assign the measured result to temp.

The serial monitor displays the temp value, and the baud rate needs to be set before displaying (our default setting is 9600, which can be changed).

We add the unit behind the data. If the unit is directly set to °C, the test result will be garbled. So we directly replace ℃ with C.

Test Result

Connect the wires according to the experimental wiring diagram, compile and upload the code to the ESP32. After uploading successfully，we will use a USB cable to power on. Open the serial monitor and set baud rate to 9600; The monitor will display the temperature of the current environment, as shown below.