Another One Day Build - Big Digital Clock

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Welcome to another digital clock build. This time I have made a big digital clock for my friend. The clock was made using programmable LED strip, cut into small pieces which would act as segments in a big 7-segment digit.

The code is on github.

Programmable LED strip

This is a very nice thing - you can set any color to the individual LED bulb on the strip:

On the picture above you can see two segments, each having four LEDs. Each LED is programmable and can be set to any color of the 16 million colors available. I have purchased two meters of W2812B LED strip and cut it in segments having four LEDs. Then I have connected all segments with three wires and created digits:

Here you can see seven segments placed temporarily on the cardboard, for the testing purposes. Then I have connected the remaining three digits and two dots between hours and minutes:

I have recycled my previous code for the LED clock so I could now set and turn on/off individual digits of my new display. Here is the main loop:

void loop() {
  setDots(counter % 2);
  setDigit(0, hour_1);
  setDigit(1, hour_2);
  setDigit(2, minute_1);
  setDigit(3, minute_2);
  delay(1000);

  counter++;
  if (counter == 2)
  {
    counter = 0;
  }
}

The code above relies on getting the current time from the DS3231 RTC, separated into hour_1, hour_2, minute_1 and minute_2 variables. Then it is just matter of setting the corresponding segments on/off:

void setDigit(int digit, int value)
{
  int i, j;
  for (i = DIGIT_IDX_START[digit]; i < (DIGIT_IDX_START[digit] + 28); i++)
  {
    j = (i - DIGIT_IDX_START[digit]) / 4;                  // j is segment index
    if (DIGIT_MATRIX[value][j])
    {
       switch (state)
      {
        case RED:
          leds[i] = CRGB(255, 0, 0);
          break;
        case GREEN:
          leds[i] = CRGB(0, 255, 0);
          break;
        case BLUE:
          leds[i] = CRGB(0, 0, 255);
          break;
        case WHITE:
          leds[i] = CRGB(255, 255, 255);
          break;
        case RAINBOW:
          leds[i] = CRGB((i % 4 + 1) * 64, (i % 4 + 2) * 64, (i % 4 + 3)* 64);
          break;
        case BLACK:
          leds[i] = CRGB(0, 0, 0);
          break;
        default:
          leds[i] = CRGB(255, 0, 0);
      }
    }
    else
    {
      leds[i] = CRGB(0, 0, 0);
    }
  }
  FastLED.setBrightness(brightness);
  FastLED.show();
}

The FastLED library works by declaring an array of LEDS in the program. Here is my array of LEDs:

#define LED_PIN     2
#define NUM_LEDS    4*28

CRGB leds[NUM_LEDS + 2];

int DIGIT_IDX_START[] = {0, 28, 56, 84};
int DIGIT_MATRIX[][7] = {
// A     B     C     D     E     F     G  
{HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, LOW},   // 0
{LOW,  HIGH, HIGH, LOW,  LOW,  LOW,  LOW},   // 1
{HIGH, HIGH, LOW,  HIGH, HIGH, LOW,  HIGH},  // 2
{HIGH, HIGH, HIGH, HIGH, LOW,  LOW,  HIGH},  // 3
{LOW,  HIGH, HIGH, LOW,  LOW,  HIGH, HIGH},  // 4
{HIGH, LOW,  HIGH, HIGH, LOW,  HIGH, HIGH},  // 5
{HIGH, LOW,  HIGH, HIGH, HIGH, HIGH, HIGH},  // 6
{HIGH, HIGH, HIGH, LOW,  LOW,  LOW,  LOW},   // 7
{HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, HIGH},  // 8
{HIGH, HIGH, HIGH, HIGH, LOW,  HIGH, HIGH},  // 9
{LOW,  LOW,  LOW,  LOW,  LOW,  LOW,  HIGH},  // '-'  index is 10
{LOW,  LOW,  LOW,  LOW,  LOW,  LOW,  LOW}    // BLANK index is 11
};

I have an array of 4*28 + 2 LEDS for 4 digits and two dots. The DIGIT_IDX_START array holds the starting indices of all four digits in that array of LEDS. 

The final look is below. I have placed a white plastic board over LEDs to disperse the light and now it is quite nice to watch in all lighting conditions:


The button at the lower right corner turns on/off the display.

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