KY-001 Temperature sensor (DS18B20)

// Required libraries will be imported
#include <OneWire.h>
#include <DallasTemperature.h>            

// Here the input pin is declared to which the sensor module is connected
#define KY001_Signal_PIN 4

// Libraries are configured
OneWire oneWire(KY001_Signal_PIN);          
DallasTemperature sensors(&oneWire);    


void setup() {

    // Initialize serial output
    Serial.begin(9600);
    Serial.println("KY-001 temperature measurement");

    // Sensor is initialized
    sensors.begin();  
}

//main program loop
void loop()
{
    // Temperature measurement is started...
    sensors.requestTemperatures();
    // ... and output measured temperature
    Serial.print("Temperature: ");
    Serial.print(sensors.getTempCByIndex(0));
    Serial.println(" °C");

    delay(1000); // 1s pause until next measurement
}

The DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with non-volatile, user-programmable high and low trigger points.

This means that the sensor has a programmable upper and lower limit. The DS18B20 communicates via a 1-wire bus, which requires only one data line for communication with a central microprocessor. In addition, the DS18B20 can draw power directly from the data line ("parasite power"). This eliminates the need for an external power source. Each DS18B20 has a unique 64-bit serial code. This allows multiple sensors to operate on the same 1-Wire bus and be evaluated by only one microprocessor.

Applications that can benefit from this feature include HVAC environmental controls, temperature monitoring systems in buildings, plants or machinery, and process monitoring and control systems.

Technical data

Chipset	DS18B20
Communication Protocol	1-Wire
Accuracy	9 to 12 Bit
Measuring range	-55 °C to +125 °C
Measurement accuracy	±0.5 °C from -10 °C to +85 °C

Pin assignment

Code example Raspberry Pi

Pin assignment Raspberry Pi:

Raspberry Pi	Sensor
GPIO4 [Pin 7]	Signal
3.3 V [Pin 1]	+V
GND [Pin 6]	GND

One-Wire Configuration Raspberry Pi

To enable the Raspberry Pi to communicate with the DS18B20 sensor via the one-wire bus, it must first be activated. To do this, enter the following command:

sudo raspi-config

Now go to Interface Options and activate the 1-Wire interface. Your Raspberry Pi should then restart automatically. Or you can use the following command to restart manually:

sudo reboot

You can now use the following example. A console output is generated as soon as a signal is detected.

This is an example program that outputs the measured temperature serially after the sensor has been initialized.

# SPDX-FileCopyrightText: 2019 Mikey Sklar for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import glob
import time

base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'

def read_temp_raw():
	f = open(device_file, 'r')
	lines = f.readlines()
	f.close()
	return lines

def read_temp():
	lines = read_temp_raw()
	while lines[0].strip()[-3:] != 'YES':
		time.sleep(0.2)
		lines = read_temp_raw()
	equals_pos = lines[1].find('t=')
	if equals_pos != -1:
		temp_string = lines[1][equals_pos+2:]
		temp_c = float(temp_string) / 1000.0
		temp_f = temp_c * 9.0 / 5.0 + 32.0
		return temp_c, temp_f

while True:
	print(read_temp())
	time.sleep(1)

Example program download

KY001-RPi.zip

To start with the command:

sudo python3 KY001-RPi.py

# Load libraries
import machine, onewire, ds18x20
from time import sleep

# Initialization of GPIO2
ds_pin = machine.Pin(10)

# Initialization of the sensor object
ds_sensor = ds18x20.DS18X20(onewire.OneWire(ds_pin))

# Search for all matching sensors
roms = ds_sensor.scan()

# Serial output
print("Found DS devices")
print("Temperature (°C)")

# Endless loop for continuous reading of the temperature
while True:
  ds_sensor.convert_temp()
  sleep(1)
  # Based on the number of compatible sensors found it will count up
  for rom in roms:
    # Serial output of the measured temperature
    print(ds_sensor.read_temp(rom))
  sleep(3)