led_bikewheel/led_bikewheel.ino

#include <FastGPIO.h>
#define APA102_USE_FAST_GPIO
#include <APA102.h>

const int HALL_PIN = 2;
const int ROUND_COUNT = 2;

// Define which pins to use.
const uint8_t dataPin = 10;
const uint8_t clockPin = 11;

// Create an object for writing to the LED strip.
APA102<dataPin, clockPin> ledStrip;

const uint16_t ledCount = 28;
const uint8_t brightness = 1;
const rgb_color RED = rgb_color(255, 0, 0);
const rgb_color GREEN = rgb_color(0, 255, 0);
const rgb_color BLUE = rgb_color(0, 0, 255);
const rgb_color WHITE = rgb_color(255, 255, 255);

const int state_count = 4;

rgb_color colors[ledCount];
float passed = 0;
int state = 0;

void setup()
{
  Serial.begin(115200);
  pinMode(HALL_PIN, INPUT);
  pinMode(LED_BUILTIN, INPUT);
}

void loop()
{
  float start = micros();
  int count = 0;
  bool change = false;
  while (count < ROUND_COUNT)
  {
    // check HALL if turned
    if (digitalRead(HALL_PIN) == LOW)
    {
      digitalWrite(LED_BUILTIN, HIGH);
      if (!change)
      {
        change = true;
        count++;
      }
    }
    else
    {
      digitalWrite(LED_BUILTIN, LOW);
      change = false;
    }

    // calc led for last turn
    float current_diff = micros() - start;

    for (int i = 0; i < state_count; i++)
    {
      if (current_diff > ((passed / state_count) * i))
      {
        state = i;
      }
    }

    rgb_color color = WHITE;

    switch (state)
    {
    case 1:
      color = RED;
      break;
    case 2:
      color = GREEN;
      break;
    case 3:
      color = BLUE;
      break;
    }

    for (uint16_t i = 0; i < ledCount; i++)
    {
      colors[i] = color;
    }

    ledStrip.write(colors, ledCount, brightness);
  }

  passed = (micros() - start);
}