As mentioned, 1-Wire is a communication protocol that allows microcontrollers and other devices to communicate through one data line and ground. It is generally used in many sensors, ADCs, and EEPROMs.

In other words, 1-Wire is a communications protocol between a single master and one or more slave devices – all of which interface to the bus using a single data line.

It is capable of half-duplex bidirectional communication. What's that? A way to think about this is to compare the use of a walkie-talkie with a mobile phone. In the case of a walkie-talkie, only one party can talk at one time. On the other hand, a mobile phone allows both parties to talk simultaneously. So with devices using 1-Wire, data can flow in either direction, but only one direction at a time.

There are three pins on the DS18B20 Digital Temperature Sensor. They are VCC, DATA, and GND.

Connect a resistor between the VCC and DATA pins of the DS18B20 Temperature Sensor.

Then connect a red jumper wire to VCC on the DS18B20 and 3.3V on Pico.

Next, connect a jumper wire to DATA on DS18B20 and GPIO16 on Pico.

Last but not least, connect a black jumper wire from GND on the DS18B20 to GND on Pico.

Import the following libraries, in previous lessons, we imported machine and time. Aside from those, you'll notice we'e also imported onewire and ds18x20.

Create a pin called ds_pin. Remember, we connected the data pin of the temperature sensor to GPIO16 on the Pico, so use 

machine.Pin(16)

The next line of code creates the onewire object.

The next line of code scans for devices on the 1-Wire bus, then prints to the shell when it has found a 1-Wire device.

According to the MicroPython documentation, you must execute the convert_temp() function to initiate a temperature reading with the DS18B20. Then wait at least 750ms before reading the value.

The final bit of code prints the temperature reading to the shell in Thonny!