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dxPwm

1. Overview​

This module is part of the official system module library of dejaOS, used for PWM (Pulse Width Modulation) control functionality. It includes comprehensive PWM control features:

  • PWM channel initialization and management
  • Power level control (0-100 range)
  • Beep sound generation with customizable parameters
  • Pre-defined beep patterns for different scenarios (press, success, fail, warning)
  • Cross-thread PWM control support

2. Files​

  • dxPwm.js
  • libvbar-b-dxpwm.so
  • Ensure these 2 files are included in the dxmodules subdirectory under your project root directory

3. Dependencies​

  • None

4. Compatible Devices​

Compatible with all devices running dejaOS v2.0+ that have PWM hardware support.

5. Usage​

Basic Usage​

import pwm from '../dxmodules/dxPwm_new.js'
import logger from '../dxmodules/dxLogger.js'
import std from '../dxmodules/dxStd.js'
import * as os from "os"

// Initialize PWM channel
pwm.init(); // channel 0

// Set power level
let power = 0
pwm.setPower(power)
os.sleep(500)

power = 50
pwm.setPower(power)
os.sleep(300)

power = 0
pwm.setPower(power)
os.sleep(500)

// Generate a simple beep
pwm.beep({
    delay: 50,
    interval: 50,
    count: 2
})

// Use pre-defined beep patterns
pwm.pressBeep();    // Short beep for key press
pwm.successBeep();  // Two short beeps for success
pwm.failBeep();     // Long beep for failure
pwm.warningBeep();  // Standard warning beep

6. API Reference​

pwm.init(channel)​

Initializes the specified PWM channel. Must be called before any other PWM operations on that channel.

Parameters:

  • channel (number): The PWM channel number to initialize, default 0

Returns: object - Initialization result object

Note: This function must be called before using any other PWM functions on the specified channel.

pwm.deinit(channel)​

Releases and cleans up the designated PWM channel.

Parameters:

  • channel (number): The PWM channel number to deinitialize, default 0

Returns: boolean - true if deinitialization successful, false otherwise

Throws: Error if channel parameter is invalid

pwm.setPower(power, channel)​

Sets the power level of the specified PWM channel.

Parameters:

  • power (number): Power level (0-100), required
  • channel (number): The PWM channel number to use, default 0

Returns: boolean - true if power set successfully, false otherwise

Throws: Error if power or channel parameters are invalid

Power Range:

  • 0: No power output
  • 1-99: Variable power levels
  • 100: Maximum power output

pwm.beep(options, channel)​

Generates a beep sound with customizable parameters.

Parameters:

  • options (object): Beep configuration parameters, optional
    • count (number): Number of beeps, default 1
    • time (number): Duration of each beep in milliseconds, default 50
    • interval (number): Interval between beeps in milliseconds, default 50
    • volume (number): Beep volume (0-100), default 50
  • channel (number): The PWM channel to use, default 0

Returns: void

Note: This function returns immediately and performs beeping in the background. The PWM channel must be initialized with pwm.init() before using this function.

Example:

// Custom beep pattern
pwm.beep({
    count: 3,      // 3 beeps
    time: 200,     // Each beep lasts 200ms
    interval: 100, // 100ms pause between beeps
    volume: 80     // 80% volume
}, 0);

pwm.pressBeep(volume, channel)​

Plays a short beep, typically used for key press feedback.

Parameters:

  • volume (number): Beep volume (0-100), default 50
  • channel (number): The PWM channel to use, default 0

Returns: void

Configuration: Single beep, 30ms duration

pwm.successBeep(volume, channel)​

Plays two short beeps, typically used to indicate successful operations.

Parameters:

  • volume (number): Beep volume (0-100), default 50
  • channel (number): The PWM channel to use, default 0

Returns: void

Configuration: Two beeps, 30ms duration each

pwm.failBeep(volume, channel)​

Plays a long beep, typically used to indicate failure or error conditions.

Parameters:

  • volume (number): Beep volume (0-100), default 50
  • channel (number): The PWM channel to use, default 0

Returns: void

Configuration: Single beep, 500ms duration

pwm.warningBeep(volume, channel)​

Plays a standard beep, typically used as a warning signal.

Parameters:

  • volume (number): Beep volume (0-100), default 50
  • channel (number): The PWM channel to use, default 0

Returns: void

Configuration: Single beep, 50ms duration

7. Constants​

No specific constants are defined in this module. However, the following ranges are used:

  • Channel Range: 0 and up (device-dependent)
  • Power Range: 0-100 (0 = no power, 100 = maximum power)
  • Volume Range: 0-100 (0 = no sound, 100 = maximum volume)

9. Example​

None.