The HC-SR04 is an inexpensive solution for measuring distances using microcontrollers. This library provides a simple driver for controlling these sensors from CircuitPython.
This driver depends on:
Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle.
Installing from PyPI¶
On supported GNU/Linux systems like the Raspberry Pi, you can install the driver locally from PyPI. To install for current user:
pip3 install adafruit-circuitpython-hcsr04
To install system-wide (this may be required in some cases):
sudo pip3 install adafruit-circuitpython-hcsr04
To install in a virtual environment in your current project:
mkdir project-name && cd project-name python3 -m venv .env source .env/bin/activate pip3 install adafruit-circuitpython-hcsr04
The HC-SR04 uses 5V logic, so you will have to use a level shifter between it and your CircuitPython board (which uses 3.3V logic).
You’ll need to dedicate two pins to communicating with the HC-SR04. The sensor communicates in a very rudimentary
manner, so it doesn’t matter which pins you choose, as long as they’re digital IO pins (pins that start with “
There are two ways of instantiating a
HCSR04 object: with or without using a context manager.
It is technically possible to communicate with the HC-SR04 using only one wire since the trigger and echo signals aren’t ever active at the same time. Once I have a chance to determine a safe way to do this, I plan to add this as a feature to the library.
- Adafruit’s guide on Lifetime and ContextManagers
Gives more info on using context managers with CircuitPython drivers.
A list of pins available on your device. To view this list, first get a REPL (the guide linked was written for the pyboard, but it still works), then input the following:import board dir(board)
Without a Context Manager¶
In the example below, we create the
HCSR04 object directly, get the distance every 2 seconds.
import time import board import adafruit_hcsr04 sonar = adafruit_hcsr04.HCSR04(trigger_pin=board.D5, echo_pin=board.D6) while True: try: print((sonar.distance,)) except RuntimeError: print("Retrying!") time.sleep(2)
With a Context Manager¶
In the example below, we use a context manager (the with statement) to create the
instance, again get the distance every 2 seconds, but then the context manager handles de-initializing the device for
import board from adafruit_hcsr04 import HCSR04 with HCSR04(trigger_pin=board.D5, echo_pin=board.D6) as sonar: try: while True: print(sonar.distance) sleep(2) except KeyboardInterrupt: pass
API documentation for this library can be found on Read the Docs.
Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.
For information on building library documentation, please check out this guide.