Big LCD Clock

By Dan Chen, January 11, 2015

I was in the store and saw the MUJI brand big LCD clock but didn’t want to pay $40 for it, so I decided to make the clock with the parts that I have around in the LAB.

I’ve got the LCD from http://moderndevice.com/product/lcd117-bundle/with the serial backpack. You can get the LCD and serial backpack from Sparkfun or http://adafruit.com as well.

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#include 


int sec=0;


int hour=1;
int minute=5;
String ampm="PM";

boolean needclear=true;


#define rxPin 4  // rxPin is immaterial - not used - just make this an unused Arduino pin number
#define txPin A0 // pin 14 is analog pin 0, on a BBB just use a servo cable :), see Reference pinMode
SoftwareSerial mySerial =  SoftwareSerial(rxPin, txPin);

void setup(){

   pinMode(txPin, OUTPUT);
   mySerial.begin(9600);      // 9600 baud is chip comm speed
   int senVal=0;  

  //hide course
  mySerial.print("?c0");
  // set LCD brightness
  mySerial.print("?B20");

}

void loop(){

      sec++;

if (sec==60){
  minute++;
  sec=0;
  needclear=true;
}
if (minute==60){
  hour++;
  minute=0;
}
if (hour==13){
    hour=1;
    if (ampm=="PM"){ampm="AM";}
    if (ampm=="AM"){ampm="PM";}
}



if (needclear){
   //clear the LCD
       mySerial.print("?f"); 
  
// enter big number mode
  mySerial.print("?>3");

   if (hour<10){mySerial.print("0");}
   mySerial.print(hour);
   mySerial.print(":");
   if (minute<10){mySerial.print("0");}
   mySerial.print(minute);
   
   //ext big number mode
   mySerial.print("?<");
   mySerial.print(ampm); 
    needclear=false;
}
    delay(1000);   

}

The LCD also work with cheap and cheerful Trinket from Adafruit. I was going to use the on board RED led as the second hand, however I can’t get it to blink and keep the time at the same time. But the below code works with Trinket. Just connect the signal pin to #3.

adafruit_products_trinket_clear_products_1500_ORIG

#include 


int sec=0;


int hour=5;
int minute=50;
String ampm="PM";

boolean needclear=true;



#define rxPin 4  // rxPin is immaterial - not used - just make this an unused Arduino pin number
#define txPin 3 // pin 14 is analog pin 0, on a BBB just use a servo cable :), see Reference pinMode
SoftwareSerial mySerial =  SoftwareSerial(rxPin, txPin);


void setup(){


   pinMode(txPin, OUTPUT);
   mySerial.begin(9600);      // 9600 baud is chip comm speed
   int senVal=0;  
  //hide course

  mySerial.print("?c0");
  mySerial.print("?B20");



}

void loop(){



   
   sec++;

if (sec==60){
  minute++;
  sec=0;
  needclear=true;
}
if (minute==60){
  hour++;
  minute=0;
}
if (hour==13){
    hour=1;
    if (ampm=="PM"){ampm="AM";}
    if (ampm=="AM"){ampm="PM";}
}



if (needclear){
     //clear the LCD

       mySerial.print("?f"); 
  
// enter big number mode
  mySerial.print("?>3");

   if (hour<10){mySerial.print("0");}
   mySerial.print(hour);
   
   mySerial.print(":");

  
   if (minute<10){mySerial.print("0");}
   mySerial.print(minute);


   
   //ext big number mode
   mySerial.print("?<");
   mySerial.print(ampm); 
    needclear=false;
}

delay(1000);


   /*
   for (byte i=0; i<256; i++){      mySerial.print("?B");       mySerial.print(i, HEX);     }    */    /*    for (byte i=255; i>0; i--){
     mySerial.print("?B"); 
     mySerial.print(i, HEX); 
   }
   
   */

}