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Smart Cities Group Project

LED Strip

This project uses an addressable LED strip (WS2812B) to provide visual feedback. The LED strip is connected to the ESP32 microcontroller, which controls the color and brightness of the LEDs based on various inputs and conditions.

Hardware Connections

  • Data Pin: Connect the data input of the LED strip to GPIO pin 5 on the ESP32.
  • Power Supply: Ensure the LED strip is powered with a suitable 5V power supply.
  • Ground: Connect the ground of the LED strip to the ground of the ESP32 to ensure a common reference point.

Software Configuration

The project uses the FastLED library to control the LED strip. Make sure to include the library in your platformio.ini file:

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lib_deps =
    FastLED

Custom Wrapper Class

A custom wrapper class LEDStrip is implemented to manage the LED strip operations.

Functions

The following functions are available in the LEDStrip class:

  • setBrightness(uint8_t brightness): Sets the brightness of the LED strip.
  • clear(): Turns off all LEDs on the strip.
  • startLoading(): Starts a loading animation on the LED strip.
  • stopLoading(): Stops the loading animation.
  • loadingAnimation(): Updates the loading animation.
  • fillColor(const CRGB &color): Fills the entire strip with a specified color.
  • toColor(const CRGB &to, unsigned long durationMs = 1000): Transitions the strip to a specified color over a given duration.
  • fillGradient(const CRGB &from, const CRGB &to): Fills the strip with a gradient between two colors.

Loading Animation

The loading animation is called in the setup loop to provide visual feedback during initialization. This is done by creating a task on a separate core of the ESP32 to ensure smooth operation without blocking other processes. The animation continues until the stopLoading() function is called.

Color Look Up Table (LUT)

A color look up table (LUT) is defined to provide a set of predefined colors for easy access. The LUT should be used with the SPS30 sensor readings to change the LED colors based on air quality levels.

The LUT is defined as follows:

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constexpr float maxPM = 250.0f;
static const GradientStop stops[] = {
    {0.0f / maxPM, 0, 255, 0},      // green
    {50.0f / maxPM, 255, 255, 0},   // yellow
    {100.0f / maxPM, 255, 165, 0},  // orange
    {150.0f / maxPM, 255, 0, 0},    // red
    {250.0f / maxPM, 128, 0, 0},  // maroon
};

This LUT can be used to map PM2.5 readings to specific colors on the LED strip, providing a visual indication of air quality.

Status Indication

This section provides a table which shows how different LED colors correspond to various system statuses

TODO: Add battery status indications.

Status State LED Color Description
SPS30 Setup Breathing Deep Sky Blue The SPS30 sensor is initializing.
SPS30 Error Blinking Deep Sky Blue The SPS30 sensor encountered an error.
SHT41 Setup Breathing Dark Blue The SHT41 sensor is initializing.
SHT41 Error Blinking Dark Blue The SHT41 sensor encountered an error.
SIM7080 Setup Breathing Purple The SIM7080 module is initializing.
SIM7080 Error Blinking Purple The SIM7080 module encountered an error.
SPS30 Reading Solid Green Normal air quality.
SPS30 Reading Solid Yellow Moderate air quality.
SPS30 Reading Solid Orange Unhealthy for sensitive groups.
SPS30 Reading Solid Red Unhealthy air quality.
SPS30 Reading Solid Maroon Very unhealthy air quality.