pigpio/test/pwm.js

Fast GPIO, PWM, servo control, state change notification, and interrupt handling on the Raspberry Pi

'use strict';

const assert = require('assert');
const pigpio = require('../');
const Gpio = require('../').Gpio;
const led = new Gpio(18, {mode: Gpio.OUTPUT});

const bcm2711 = pigpio.hardwareRevision() === 0xa03111;

assert.strictEqual(led.getPwmRange(), 255, 'expected pwm range to be 255');
assert.strictEqual(led.getPwmRealRange(), 250, 'expected pwm real range to be 250');
assert.strictEqual(led.getPwmFrequency(), 800, 'expected get pwm frequency to be 800');

led.pwmRange(125);
assert.strictEqual(led.getPwmRange(), 125, 'expected pwm range to be 125');
assert.strictEqual(led.getPwmRealRange(), 250, 'expected pwm real range to be 250');
assert.strictEqual(led.getPwmFrequency(), 800, 'expected get pwm frequency to be 800');

led.pwmFrequency(2000);
assert.strictEqual(led.getPwmRange(), 125, 'expected pwm range to be 125');
assert.strictEqual(led.getPwmRealRange(), 100, 'expected pwm real range to be 100');
assert.strictEqual(led.getPwmFrequency(), 2000, 'expected get pwm frequency to be 2000');

const dutyCycle = Math.floor(led.getPwmRange() / 2);
led.pwmWrite(dutyCycle);
assert.strictEqual(led.getPwmDutyCycle(), dutyCycle, 'expected duty cycle to be ' + dutyCycle);

led.hardwarePwmWrite(1e7, 500000);
const hardwareClockFrequency = bcm2711 ? 375000000: 250000000;
const expectedRealRange = Math.round(hardwareClockFrequency / 1e7);
const expectedFrequency = Math.round(hardwareClockFrequency / expectedRealRange);
assert.strictEqual(led.getPwmRange(), 1e6, 'expected pwm range to be 1e6');
assert.strictEqual(led.getPwmRealRange(), expectedRealRange, 'expected pwm real range to be ' + expectedRealRange);
assert.strictEqual(led.getPwmFrequency(), expectedFrequency, 'expected get pwm frequency to be ' + expectedFrequency);
assert.strictEqual(led.getPwmDutyCycle(), 500000, 'expected duty cycle to be 500000');

led.digitalWrite(0);
assert.strictEqual(led.getPwmRange(), 125, 'expected pwm range to be 125');
assert.strictEqual(led.getPwmRealRange(), 100, 'expected pwm real range to be 100');
assert.strictEqual(led.getPwmFrequency(), 2000, 'expected get pwm frequency to be 2000');