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.
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, then
de-initialize the device.
from adafruit_hcsr04 import HCSR04 sonar = HCSR04(trig, echo) try: while True: print(sonar.dist_cm()) sleep(2) except KeyboardInterrupt: pass sonar.deinit()
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
from adafruit_hcsr04 import HCSR04 with HCSR04(trig, echo) as sonar: try: while True: print(sonar.dist_cm()) sleep(2) except KeyboardInterrupt: pass
Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.
Zip release files¶
To build this library locally you’ll need to install the circuitpython-build-tools package.
python3 -m venv .env source .env/bin/activate pip install circuitpython-build-tools
Once installed, make sure you are in the virtual environment:
Then run the build:
circuitpython-build-bundles --filename_prefix adafruit-circuitpython-hcsr04 --library_location .
Sphinx is used to build the documentation based on rST files and comments in the code. First, install dependencies (feel free to reuse the virtual environment from above):
python3 -m venv .env source .env/bin/activate pip install Sphinx sphinx-rtd-theme
Now, once you have the virtual environment activated:
cd docs sphinx-build -E -W -b html . _build/html
This will output the documentation to
docs/_build/html. Open the index.html in your browser to
view them. It will also (due to -W) error out on any warning like Travis will. This is a good way to
locally verify it will pass.