Particle LED Energy Saver

A small blink pattern library to reduce the energy used by the Particle status LED

This class is used like any other custom blink pattern class in the Particle environment. (See https://docs.particle.io/reference/firmware/photon/#ledstatus-class)

Special attention has been paid to making this work correctly even when the CPU is severely throttled.

Description

This custom Status LED pattern will blink ON for about 50ms and OFF for about 100ms for each flash that is specified.

50ms is approximately the optimal on-time to register with maximum brightness in the eye, and 100ms provides enough off-time to easily distinguish the number of flashes.

For example, if Period is 1000 and #Flashes is 3, the blink pattern will be:

    |--------350ms-------|-------------650ms------------------|
ON  ___      ___      ___
OFF    ______   ______   _____________________________________
    |----------------------1000 ms----------------------------|

Caution: This library does not make an effort to filter nonsensical parameters, so make sure at least that

Period > 150ms x #Flashes.

Constructors:

LEDStatusEnergySaver( Priority, Color )

• Defaults to 1 flash, 1-second period

LEDStatusEnergySaver( Priority, Color, Period )

• Defaults to 1 flash

LEDStatusEnergySaver( Priority, Color, Period, #Flashes )

• Fully specified by parameters

Priority

See Particle Documentation on the LEDPriority Enum.

LEDPriority Value Name	Description
LED_PRIORITY_BACKGROUND	long-lasting background indications
LED_PRIORITY_NORMAL	regular, typically short indications
LED_PRIORITY_IMPORTANT	important indications
LED_PRIORITY_CRITICAL	critically important indications

Color

uint32_t

See Particle documentation on the Color parameter.

A color value with the red, green, and blue intensities packed in the format 0x00RRGGBB.

Particle color constants	Description	Value
RGB_COLOR_BLUE	blue	0x000000ff
RGB_COLOR_GREEN	green	0x0000ff00
RGB_COLOR_CYAN	cyan	0x0000ffff
RGB_COLOR_RED	red	0x00ff0000
RGB_COLOR_MAGENTA	magenta	0x00ff00ff
RGB_COLOR_YELLOW	yellow	0x00ffff00
RGB_COLOR_WHITE	white	0x00ffffff
RGB_COLOR_GRAY	gray	0x001f1f1f
RGB_COLOR_ORANGE	orange	0x00ff6000

Period

uint32_t

Repetition rate in number of milliseconds.

Number of Flashes

uint8_t

The number of flashes to consecutively blink, separated by 100ms. There is no facility for flashing different colors in a flash repetition.

Using different numbers of flashes for different statuses is encouraged as an accommodation to color-blind users.

Usage:

// Declaration
LEDStatusEnergySaver LEDLowPowerSensorEnabled(
        LED_PRIORITY_NORMAL,    // Special status patterns will take priority
        0x0000ff00,             // Green
        1000,                   // 1-second period
        1);                     // 1 flash per period
LEDStatusEnergySaver LEDLowPowerSensorDisabled(
        LED_PRIORITY_NORMAL,    // Special status patterns will take priority
        0x00ff00ff,             // Magenta
        1000,                   // 1-second period
        2);                     // 2 flashes per period


// Return to default status LED behavior
void stateA() {
  LEDLowPowerSensorEnabled.setActive(false);
  LEDLowPowerSensorDisabled.setActive(false);
}

// Blink 1 green
void stateB() {
  LEDLowPowerSensorEnabled.setActive(true);
}

// Blink 2 magenta
void stateC() {
  LEDLowPowerSensorDisabled.setActive(true);
}