vineri, 21 iunie 2013

Afisaje LED cu 7 segmente si.. Arduino

   Pentru afisarea unor informatii numerice, se pot folosi clasicele afisaje LED cu 7 segmente, deoarece au dimensiuni mari, sunt vizibile cand este lumina putina sau deloc, dar ziua se vad mai greu, dar li se pot pune filtre... oriucum sunt mai ieftine decat afisajele cu cristale lichide (LCD).
   Am ales un afisaj cu 4 cifre multiplexate, cu anod comun, fabricat de Luckylight, avand codul KW4-563ASA, pe care l-am cumparat de la TME.

   Pe Pagina lui Timofte Andrei este un exemplu de de numarator, a carei sursa de inspiratie se gaseste la http://www.hobbytronics.co.uk/arduino-4digit-7segment.
   Dupa ce am studiat datasheet-ul afisajului meu si am comparat cu programul original care comanda un afisaj cu pinii asezati altfel, am refacut conexiunile, inclusiv sketch-ul.
   Dupa cum se observă, in această schemă nu se folosesc rezistente de limitare, ci se foloseste controlul curentului prin varierea factorului de umplere (PWM) pentru fiecare grup LED-uri.
 
/*
 6-13-2011
 Spark Fun Electronics 2011
 Nathan Seidle

 This code is public domain but you buy me a beer if you use this and we meet 
 someday (Beerware license).

 4 digit 7 segment display:
 http://www.sparkfun.com/products/9483
 Datasheet: 
 http://www.sparkfun.com/datasheets/Components/LED/7-Segment/YSD-439AR6B-35.pdf

 This is an example of how to drive a 7 segment LED display from an ATmega
 without the use of current limiting resistors. This technique is very common 
 but requires some knowledge of electronics - you do run the risk of dumping 
 too much current through the segments and burning out parts of the display. 
 If you use the stock code you should be ok, but be careful editing the 
 brightness values.

 This code should work with all colors (red, blue, yellow, green) but the 
 brightness will vary from one color to the next because the forward voltage 
 drop of each color is different. This code was written and calibrated for the 
 red color.

 This code will work with most Arduinos but you may want to re-route some of 
 the pins.

 7 segments
 4 digits
 1 colon
 =
 12 pins required for full control 

 */
// modified connexion by niq_ro from http://nicuflorica.blogspot.com
// for my Luckylight KW4-563ASA
// dataseet: http://www.tme.eu/ro/Document/dfc2efde2e22005fd28615e298ea2655/KW4-563XSA.pdf

int digit1 = 11; //PWM Display pin 12
int digit2 = 10; //PWM Display pin 9
int digit3 = 9; //PWM Display pin 8
int digit4 = 6; //PWM Display pin 6

//Pin mapping from Arduino to the ATmega DIP28 if you need it
//http://www.arduino.cc/en/Hacking/PinMapping
int segA = A1; //Display pin 11
int segB = 3; //Display pin 7
int segC = 4; //Display pin 4
int segD = 5; //Display pin 2
int segE = A0; //Display pin 1
int segF = 7; //Display pin 10
int segG = 8; //Display pin 5

void setup() {                
  pinMode(segA, OUTPUT);
  pinMode(segB, OUTPUT);
  pinMode(segC, OUTPUT);
  pinMode(segD, OUTPUT);
  pinMode(segE, OUTPUT);
  pinMode(segF, OUTPUT);
  pinMode(segG, OUTPUT);

  pinMode(digit1, OUTPUT);
  pinMode(digit2, OUTPUT);
  pinMode(digit3, OUTPUT);
  pinMode(digit4, OUTPUT);
  
  pinMode(13, OUTPUT);
}

void loop() {
  
  //long startTime = millis();

  displayNumber(millis()/1000);

  //while( (millis() - startTime) < 2000) {
  //displayNumber(1217);
  //}
  //delay(1000);  
}

//Given a number, we display 10:22
//After running through the 4 numbers, the display is left turned off

//Display brightness
//Each digit is on for a certain amount of microseconds
//Then it is off until we have reached a total of 20ms for the function call
//Let's assume each digit is on for 1000us
//Each digit is on for 1ms, there are 4 digits, so the display is off for 16ms.
//That's a ratio of 1ms to 16ms or 6.25% on time (PWM).
//Let's define a variable called brightness that varies from:
//5000 blindingly bright (15.7mA current draw per digit)
//2000 shockingly bright (11.4mA current draw per digit)
//1000 pretty bright (5.9mA)
//500 normal (3mA)
//200 dim but readable (1.4mA)
//50 dim but readable (0.56mA)
//5 dim but readable (0.31mA)
//1 dim but readable in dark (0.28mA)

void displayNumber(int toDisplay) {
#define DISPLAY_BRIGHTNESS  500

#define DIGIT_ON  HIGH
#define DIGIT_OFF  LOW

  long beginTime = millis();

  for(int digit = 4 ; digit > 0 ; digit--) {

    //Turn on a digit for a short amount of time
    switch(digit) {
    case 1:
      digitalWrite(digit1, DIGIT_ON);
      break;
    case 2:
      digitalWrite(digit2, DIGIT_ON);
      break;
    case 3:
      digitalWrite(digit3, DIGIT_ON);
      break;
    case 4:
      digitalWrite(digit4, DIGIT_ON);
      break;
    }

    //Turn on the right segments for this digit
    lightNumber(toDisplay % 10);
    toDisplay /= 10;

    delayMicroseconds(DISPLAY_BRIGHTNESS); 
    //Display digit for fraction of a second (1us to 5000us, 500 is pretty good)

    //Turn off all segments
    lightNumber(10); 

    //Turn off all digits
    digitalWrite(digit1, DIGIT_OFF);
    digitalWrite(digit2, DIGIT_OFF);
    digitalWrite(digit3, DIGIT_OFF);
    digitalWrite(digit4, DIGIT_OFF);
  }

  while( (millis() - beginTime) < 10) ; 
  //Wait for 20ms to pass before we paint the display again
}

//Given a number, turns on those segments
//If number == 10, then turn off number
void lightNumber(int numberToDisplay) {

#define SEGMENT_ON  LOW
#define SEGMENT_OFF HIGH

  switch (numberToDisplay){

  case 0:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_ON);
    digitalWrite(segE, SEGMENT_ON);
    digitalWrite(segF, SEGMENT_ON);
    digitalWrite(segG, SEGMENT_OFF);
    break;

  case 1:
    digitalWrite(segA, SEGMENT_OFF);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_OFF);
    digitalWrite(segE, SEGMENT_OFF);
    digitalWrite(segF, SEGMENT_OFF);
    digitalWrite(segG, SEGMENT_OFF);
    break;

  case 2:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_OFF);
    digitalWrite(segD, SEGMENT_ON);
    digitalWrite(segE, SEGMENT_ON);
    digitalWrite(segF, SEGMENT_OFF);
    digitalWrite(segG, SEGMENT_ON);
    break;

  case 3:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_ON);
    digitalWrite(segE, SEGMENT_OFF);
    digitalWrite(segF, SEGMENT_OFF);
    digitalWrite(segG, SEGMENT_ON);
    break;

  case 4:
    digitalWrite(segA, SEGMENT_OFF);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_OFF);
    digitalWrite(segE, SEGMENT_OFF);
    digitalWrite(segF, SEGMENT_ON);
    digitalWrite(segG, SEGMENT_ON);
    break;

  case 5:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_OFF);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_ON);
    digitalWrite(segE, SEGMENT_OFF);
    digitalWrite(segF, SEGMENT_ON);
    digitalWrite(segG, SEGMENT_ON);
    break;

  case 6:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_OFF);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_ON);
    digitalWrite(segE, SEGMENT_ON);
    digitalWrite(segF, SEGMENT_ON);
    digitalWrite(segG, SEGMENT_ON);
    break;

  case 7:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_OFF);
    digitalWrite(segE, SEGMENT_OFF);
    digitalWrite(segF, SEGMENT_OFF);
    digitalWrite(segG, SEGMENT_OFF);
    break;

  case 8:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_ON);
    digitalWrite(segE, SEGMENT_ON);
    digitalWrite(segF, SEGMENT_ON);
    digitalWrite(segG, SEGMENT_ON);
    break;

  case 9:
    digitalWrite(segA, SEGMENT_ON);
    digitalWrite(segB, SEGMENT_ON);
    digitalWrite(segC, SEGMENT_ON);
    digitalWrite(segD, SEGMENT_ON);
    digitalWrite(segE, SEGMENT_OFF);
    digitalWrite(segF, SEGMENT_ON);
    digitalWrite(segG, SEGMENT_ON);
    break;

  case 10:
    digitalWrite(segA, SEGMENT_OFF);
    digitalWrite(segB, SEGMENT_OFF);
    digitalWrite(segC, SEGMENT_OFF);
    digitalWrite(segD, SEGMENT_OFF);
    digitalWrite(segE, SEGMENT_OFF);
    digitalWrite(segF, SEGMENT_OFF);
    digitalWrite(segG, SEGMENT_OFF);
    break;
  }
}

   Am facut un film demonstrativ, care se numeste counter with 7 segment LED and Arduino

   Articole interesante si cu explicatii se gasesc la:
- hacktronics.com
makezine.com
dfrobot.com
learn.parallax.com
oscarliang.net
25.06.2013
   Pentru a putea folosi la maxim modul de afisare al acestui tip de afisaj cu cifre de 7 segmente conectate pentru comanda multiplexata, se utilizeaza libraria SevSeg.




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