DS18B20 with Raspberry Pi Pico

What is DS18B20?

The DS18B20 is a 1-wire programmable temperature sensor from Maxim integrated that requires only one data line for communication with a central microprocessor. Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18B20s distributed over a large area.

 

Applications

  1. Thermostatic Controls
  2. Industrial Systems
  3. Consumer Products
  4. Thermometers
  5. Thermally Sensitive Systems

Material Required is as follows:

1.Raspberry Pi Pico

2.DS18B20

Circuit Diagram

  1. Connect the sensor's ground to one of the ground pins on the Pico.
  2. Connect the sensor's VCC pin to the Pico's 3.3V(out) pin.
  3. Connect the Sensor's data pin to the Pico's GPIO22

 Code and Library

 Setup library

  1. For DS18B20 we need OneWire and DS18X20 libraries. Download from the link below     https://github.com/micropython/micropython/tree/master/drivers/onewire  
  2. Visit the link for the respective library.
  3. Click on the file present inside the downloaded folder and then copy the contents of the entire file .
  4. Click on the “New” button on the Thonny IDE to open a blank script and paste the copied code.
  5. Click on the save button and when prompted to choose
  6. When asked for save location, choose Raspberry Pi Pico.4
  7. Once the dialog box opens to choose the save location on the Pico, double click on the “lib” folder present already to save the file inside it. If the lib folder does not exist, create it and then save the file inside it.
  8. Enter the same name for the file as on the GitHub repo and press the Ok button. To add the downloaded library, open Thonny and navigate to the following directory in the Pico.

Thonny > File > Open > Raspberry Pi Pico > lib

  1. Copy the library code and save the file with .py extension.

 Code

         import machine, onewire, ds18x20, time

ds_pin = machine.Pin(22)

ds_sensor = ds18x20.DS18X20(onewire.OneWire(ds_pin))

roms = ds_sensor.scan()

print('Found DS devices: ', roms)

while True:

  ds_sensor.convert_temp()

  time.sleep_ms(750)

  for rom in roms:

    print(rom)

    print(ds_sensor.read_temp(rom))

  time.sleep(5)

Copy the above code into thonny ide and run the code.

You can see output into Thonny Shell

Troubleshooting

After executing the program and error still occurs, like the one below.

Solution: Check your connections, make sure the connections are correct and not loose. Also, check-in the code if the pin number is correct.

 

 

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