"Fiat Lux - Hãy có ánh sáng": (Phần 4) Đồng hồ Arduino với neopixel WS2812

• Để làm đồng hồ thông thường với Arduino thì ta cần phải có module thời gian thực (RTC). Tuy nhiên, ta có thể sử dụng 1 library khá hữu dụng tên là Time.h từ đây. Library này sử dụng hàm millis() để tính thời gian. 
• Ta sẽ dùng module Neopixel Ring gồm 24 module WS2812 nối lại với nhau và sử dụng thuật toán modulo (%) để tính vị trí của các kim giây, phút, giờ và ra lệnh cho module qua cổng digital.

• Các bạn vào đây và download thư viện
• Code thoai:

#include <Adafruit_NeoPixel.h>
#include <Time.h>  
//Modified by MonsieurVechai


//////////////////////////////////////////////////////////////
////////            LED RING DEFINITION                 //////
//////////////////////////////////////////////////////////////
#define PIN A0
const uint16_t number_of_pixels = 24;
uint16_t hour_clock, minute_clock, second_clock; 

// Parameter 1 = number of pixels in strip
// Parameter 2 = pin number 
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_RGB     Pixels are wired for RGB bitstream
//   NEO_GRB     Pixels are wired for GRB bitstream
//   NEO_KHZ400  400 KHz bitstream (e.g. FLORA pixels)
//   NEO_KHZ800  800 KHz bitstream (e.g. High Density LED strip)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(number_of_pixels, PIN, NEO_GRB + NEO_KHZ800);

// Here we set the DEFAULT colors of the clock arms. In general, the larger the numbers, the brigher the clock is
uint32_t milli_color  = strip.Color ( 2,  10,  5);
uint32_t second_color = strip.Color (  0,  0, 10);
uint32_t minute_color = strip.Color ( 0, 10, 0);
uint32_t hour_color   = strip.Color (  10, 0,  0);
uint32_t off_color    = strip.Color (  0,  0,  0);

/* CLOCK POSITION OBJECT*/
class ClockPositions
{
 public:
  uint8_t milli;
  uint8_t second_clock;
  uint8_t minute_clock;
  uint8_t hour_clock;
  ClockPositions ();
  void update    ();
};


ClockPositions::ClockPositions()
{
  milli = second_clock = minute_clock = hour_clock = 0;
}

void ClockPositions::update()
{
  hour_clock   = map (hour() % 12, 0,  12, 0, number_of_pixels); //get hour from the <Time.h> library
  minute_clock = map (minute() % 60, 0,  60, 0, number_of_pixels); //get minute from the <Time.h> library
  second_clock = map ((second() % 60), 0, 60, 0, number_of_pixels); //conventional second clock 
  milli  = map ((millis() %  1000), 0,  1000, 0, number_of_pixels); 
}

/* CLOCK VIEW OBJECT*/

class ClockSegments
{
 public:
  ClockPositions    &positions;
  Adafruit_NeoPixel &strip;
  ClockSegments (Adafruit_NeoPixel&, ClockPositions&);
  void draw  ();
  void clear ();
  void add_color (uint8_t position, uint32_t color);
  uint32_t blend (uint32_t color1, uint32_t color2);
};


ClockSegments::ClockSegments (Adafruit_NeoPixel& n_strip, ClockPositions& n_positions): strip (n_strip), positions (n_positions)
{
}


void ClockSegments::draw()
{
  clear();
  add_color (positions.hour_clock     % number_of_pixels,  hour_color  );
    
  add_color (positions.minute_clock   % number_of_pixels,  minute_color);

  add_color (positions.second_clock     % number_of_pixels, second_color);
  
  add_color (positions.milli     % number_of_pixels,  milli_color);

  strip.show ();
}


void ClockSegments::add_color (uint8_t position, uint32_t color)
{
  uint32_t blended_color = blend (strip.getPixelColor (position), color);

  /* Gamma mapping */
  uint8_t r,b,g;

  r = (uint8_t)(blended_color >> 16),
  g = (uint8_t)(blended_color >>  8),
  b = (uint8_t)(blended_color >>  0);

  strip.setPixelColor (position, blended_color);
}


uint32_t ClockSegments::blend (uint32_t color1, uint32_t color2)
{
  uint8_t r1,g1,b1;
  uint8_t r2,g2,b2;
  uint8_t r3,g3,b3;

  r1 = (uint8_t)(color1 >> 16),
  g1 = (uint8_t)(color1 >>  8),
  b1 = (uint8_t)(color1 >>  0);

  r2 = (uint8_t)(color2 >> 16),
  g2 = (uint8_t)(color2 >>  8),
  b2 = (uint8_t)(color2 >>  0);

  return strip.Color (constrain (r1+r2, 0, 255), constrain (g1+g2, 0, 255), constrain (b1+b2, 0, 255));
}


void ClockSegments::clear ()
{
  for(uint8_t i=0; i<strip.numPixels (); i++) {
      strip.setPixelColor (i, off_color);
  }
}

/* APP */
ClockPositions positions;
ClockSegments  segments(strip, positions);
////////////////////////////////////////////////////
/////       END OF LED RING DEFINITION      ////////
////////////////////////////////////////////////////



void setup ()
{  
  strip.begin ();
  strip.show(); // Initialize all pixels to 'off'
  setTime(20, 10, 0, 19, 7, 2016);
}


void loop ()
{
  positions.update ();
  segments.draw ();
}