How to debounce a button using onoff?

Use the debounceTimeout option when creating a Gpio object for the button. Set it to a millisecond value, like 10ms, to delay the watch callback until the input stabilizes, as shown in the debouncing example.

onoff vs pigpio: which is better for Raspberry Pi?

onoff is simpler and works across multiple boards using sysfs, while pigpio is faster and offers more features like PWM but is Raspberry Pi-specific. Choose onoff for cross-platform projects or pigpio for high-performance on Pi.

Can I use onoff with Node.js 18?

The README states support for Node.js versions 10 to 16, so Node.js 18 might not be officially tested. Check the GitHub repository for updates or compatibility notes before upgrading.

How to handle hardware interrupts with onoff?

Use the watch method on a Gpio object configured with an edge ('rising', 'falling', or 'both'). The callback receives the pin state on interrupt, as demonstrated in the button and LED example.

What boards are compatible with onoff?

Tested on Raspberry Pi 1-4 and BeagleBone boards running Raspbian, Raspberry Pi OS, or Debian. It may work on other Linux boards with sysfs GPIO support, but compatibility isn't guaranteed.

How to mock GPIO access in development with onoff?

Check the Gpio.accessible property. If false, create mock objects that mimic the Gpio API, as shown in the accessibility check example with a virtual LED.

How to configure pullup resistors with onoff?

onoff doesn't provide this directly. Use external methods like editing /boot/config.txt on Raspberry Pi or device tree overlays, as described in the README's configuration section.

Open-Awesome

onoff

MITJavaScript

A Node.js library for GPIO access and interrupt detection on Linux boards like Raspberry Pi and BeagleBone.

GitHub

1.3k stars124 forks0 contributors

What is onoff?

onoff is a Node.js library that provides GPIO (General Purpose Input/Output) access and interrupt detection for Linux-based single-board computers like the Raspberry Pi and BeagleBone. It allows developers to read from and write to GPIO pins, handle hardware interrupts, and debounce button inputs, solving the problem of interfacing JavaScript applications with physical hardware.

Target Audience

Developers working on IoT projects, robotics, or hardware prototyping who need to control and monitor GPIO pins from Node.js applications on Linux boards.

Value Proposition

Developers choose onoff for its straightforward API, support for both synchronous and asynchronous operations, built-in debouncing, and reliable performance across popular platforms like Raspberry Pi and BeagleBone, making hardware interaction accessible from Node.js.

Overview

GPIO access and interrupt detection with Node.js

Use Cases

Best For

Controlling LEDs and reading button states on Raspberry Pi
Building IoT devices with Node.js and GPIO
Handling hardware interrupts for sensor inputs
Prototyping robotics projects with BeagleBone
Debouncing mechanical switches in embedded applications
Mocking GPIO functionality in development environments

Not Ideal For

Projects requiring high-frequency GPIO toggling above 20kHz
Non-Linux systems or boards without the sysfs GPIO interface
Applications needing integrated pullup/pulldown resistor configuration

Pros & Cons

Pros

Intuitive GPIO Control

Provides simple read/write methods and interrupt handling with a clean API, as demonstrated in the LED and button examples using watch and writeSync.

Built-in Debouncing

Includes a debounceTimeout option to handle button bounce issues, shown in the debouncing example where it delays callbacks until input stabilizes.

Cross-Platform SBC Support

Tested on Raspberry Pi (1-4) and BeagleBone boards with various Node.js versions, ensuring reliability on popular hardware as listed in benchmarks.

Mockability for Development

The Gpio.accessible property allows easy mocking when GPIO access isn't available, facilitating development on non-Linux systems with virtual LEDs.

Cons

Sysfs Dependency Limits Portability

Relies on the Linux sysfs interface at /sys/class/gpio, which is optional and may not be available on all Linux boards, reducing compatibility.

Missing Hardware Configuration Features

Does not support configuring pullup and pulldown resistors directly; developers must use platform-specific methods outside the library, as admitted in the README.

Performance Constraints for High-Speed Apps

Benchmarks show maximum interrupt detection around 20k per second, which may be insufficient for applications requiring very rapid signal processing compared to alternatives like pigpio.

Frequently Asked Questions

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