This example demonstrates how to use 1-Wire devices with the Raspberry Pi Pico (RP2040). 1-Wire is an interface that enables a master to control several slave devices over a simple shared serial bus.
The example provides a 1-Wire library that is used to take readings from a set of connected DS18B20 1-Wire temperature sensors. The results are sent to the default serial terminal connected via USB or UART as configured in the SDK.
The library uses a driver based on the RP2040 PIO state machine to generate accurate bus timings and control the 1-Wire bus via a GPIO pin.
1-Wire® is a registered trademark of Maxim Integrated Products, Inc.
Connect one or more DS18B20 sensors to the Pico as shown in the diagram and table below.
Connect GPIO 15 to 3V3(OUT) with a pull-up resistor of about 4k ohms.
| Pico | pin | DS18B20 | pin / sensor wire |
|---|---|---|---|
GND |
38 or equivalent |
GND |
1 / Black |
GPIO 15 |
20 |
DQ |
2 / Yellow |
3V3(OUT) |
36 |
VDD |
3 / Red |
Item |
Quantity |
Details |
Breadboard |
1 |
generic part |
Raspberry Pi Pico |
1 |
|
DS18B20 |
3 |
chip or wired sensor |
3900 ohm resistor |
1 |
generic part |
M/M jumper wire |
13 |
generic part |
- CMakeLists.txt
-
CMake file to incorporate the example in the build tree.
- onewire.c
-
Source code for the example program.
- ow_rom.h
-
Header file with generic ROM command codes for 1-Wire devices.
- ds18b20.h
-
Header file with function command codes for the DS18B20 device.
- onewire_library/
-
Subdirectory containing the 1-Wire library and driver.
- onewire_library/CMakeLists.txt
-
CMake file to build the 1-Wire library and driver.
- onewire_library/onewire_library.c
-
Source code for the 1-Wire user functions.
- onewire_library/onewire_library.h
-
Header file for the 1-Wire user functions and types.
- onewire_library/onewire_library.pio
-
PIO assembly code for the 1-Wire driver.