opengpio
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A performant c++ based general purpose GPIO controller for linux devices. OpenGPIO is written using libgpiod, line & chip based abstractions.
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JavaScript
import { Edge } from '../types';
import { bindings } from '../bindings';
import { GpioDriver } from './GpioDriver';
import { DriverStoppedError } from '../errors/DriverStoppedError';
/**
* Represents a GPIO watcher that monitors edge changes (rising, falling, or both).
* Extends the `GpioDriver` class to provide event-driven functionality for GPIO inputs.
*/
export class Watch extends GpioDriver {
/**
* Constructs a `Watch` instance.
*
* @param gpio - The GPIO pin configuration, including chip and line information.
* @param edge - The edge type to monitor (rising, falling, or both).
* @param options - Configuration options for the watcher, such as debounce and bias.
*/
constructor(gpio, edge, options = {}) {
var _a, _b;
const [getter, cleanup] = bindings.watch(gpio.chip, gpio.line, (_a = options.debounce) !== null && _a !== void 0 ? _a : 0, (_b = options.bias) !== null && _b !== void 0 ? _b : 0, (value) => {
this.debug('watcher callback with value', value);
if (value && (edge === Edge.Rising || edge === Edge.Both)) {
this.debug('value is true, emitting rise and change');
// Emits events for a rising edge
this.emit('change', value);
this.emit('rise', value);
}
else if (!value && (edge === Edge.Falling || edge === Edge.Both)) {
this.debug('value is false, emitting fall and change');
// Emits events for a falling edge
this.emit('change', value);
this.emit('fall', value);
}
});
super(cleanup);
this.edge = edge;
/**
* A function to retrieve the current value of the GPIO pin.
* Defaults to a function that always returns `false`.
* @private
*/
this.getter = () => false;
this.debug('constructing watcher with', gpio, edge, options);
this.getter = getter;
}
/**
* Gets the current value of the GPIO pin being watched.
*
* @throws {DriverStoppedError} If the watcher has been stopped.
* @returns The current value of the GPIO pin (`true` for high, `false` for low).
*/
get value() {
this.debug('getting watcher value');
if (this.stopped) {
this.debug('watcher is stopped, throwing error');
throw new DriverStoppedError('Cannot get value from stopped watcher');
}
const value = this.getter();
this.debug('watcher value is', value);
return value;
}
}
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