LCD 4bit, Arduino, Shift register – Mikrokontroléry – Fórum – Programujte.com

Ahoj,

rozchodil jsem si LCD s radicem 7066 s Arduinem pres 8bit shiftregister. Nicmene v jedne chvili inicializace (v kodu asi tri odstavce ke konci, okomentovane otazniky) musim dat cekani ~1000us, aby se mi displej zapnul. Vse ostatni slape bez zpozdeni, zkousel jsem i vysoke hodnoty cekani pri trojitem initu, abych overil, zda se mi displej inicializuje spravne, ale vysledek je stejny. Co to muze znamenat?

void init4bit()
{
  //first init
  delay(50);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 67);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 3);
  digitalWrite(latchPin, HIGH);

  //second init
  delay(5);  
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 67);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 3);
  digitalWrite(latchPin, HIGH);
  
  //third init
  delay(1);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 67);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 3);
  digitalWrite(latchPin, HIGH);

  //set 4bit mode
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 66);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 2);
  digitalWrite(latchPin, HIGH);

  //set 4bit mode, set 2line display
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 66);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 2);
  digitalWrite(latchPin, HIGH);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 72);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 8);
  digitalWrite(latchPin, HIGH);

  //clear display
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 64);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0);
  digitalWrite(latchPin, HIGH);
  
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 65);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 1);
  digitalWrite(latchPin, HIGH);
  
  //display off
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 64);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0);
  digitalWrite(latchPin, HIGH);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 72);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 8);
  digitalWrite(latchPin, HIGH);

  //display on
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 64);
  digitalWrite(latchPin, HIGH);
  delayMicroseconds(900);                    //???????????????????
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0);
  digitalWrite(latchPin, HIGH);
  
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 76);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 12);
  digitalWrite(latchPin, HIGH);

  //entry mode set
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 64);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0);
  digitalWrite(latchPin, HIGH);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 70);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 6);
  digitalWrite(latchPin, HIGH);

  //write "D"
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 128+64+4);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 128+4);
  digitalWrite(latchPin, HIGH);
 
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 128+64+4);
  digitalWrite(latchPin, HIGH);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 128+4);
  digitalWrite(latchPin, HIGH);
}

muzes se tema latch pulzama dostat uplne mimo specku.. vetsinou je presne definovana minimalni delka pulzu a kdyz bude treba pri 20MHz 50ns, tak uz to muze byt trochu malo

no koukam na datasheet a minimalni sirka pulzu je na E 150ns coz odpovida taktu neco pres 6MHz maximum..

Diky za rychlou reakci, chapu.

Nicmene se deje to, ze to zpozdeni nemuzu snizit pod 900ms, aby to fungovalo...preci uz delka 100us pro E je temer tisicinasobne vetsi, nez udava datasheet. Navic se mi to deje jen v tomhle konkretnim pripade, cely zbytek kodu (v podstate identicky) se chova spravne. Po pohledani googlu jsem navic zjistil, ze na Arduinu dve po sobe nasledujici volani digitalWrite trvaji ca 2,5us, coz je taky oproti 150ns nesmirne dlouho. Nemyslim si teda, ze by to byla chyba casovani pulzu E.

#4 Dynko
jo vidis, mas pravdu ze na arduinu je to blbnuti s pinama priserne pomaly

kazdopadne na posilani prikazu/dat bych si udelal klidne funkce.. a pokud vim, tak vic problemu bylo spis s casovanim po odeslani commandu ne uprostred

mozna bych zkusil primo nejakou libku pro arduino a pripojit display primo (bez toho posuvnyho registru) a pokud to bude fungovat dobre, tak pak teprve resit vlastni kod (taky bez toho shift registru, az pak s nim)