Calculator

Heyho! So here I am again and this post is about my story in doing my 4th mission for my Human Computer Interaction Class.

The 4th mission is making a calculator where the input come from keypad and the output has to be displayed on LCD. I hate keypad and LCD as well as I hate 7-segment. They need so many wires and it always confuses me. The wires are cute indeed since they are colorful. Yet....it is hard for me huhuhuhu I already had bad feeling when we decided to make this mission on Friday, before Friday prayers. But we did not have anytime anymore since examination is near already. So we gave it a try. We found a website that provide us a good tutorial to finish our 4th project. We found it on www.microcontroller-project.com/calculator-using-arduino.html. As usual, here are things that you have to prepare.

As usual, again, you have to make a series. Below is the schema that we get from the same website. Oh, there is also the source code. Feel free to copy yet you have to remember that all the credit goes to www.microcontroller-project.com/calculator-using-arduino.html.

#include <LiquidCrystal.h> #include <Keypad.h> int getKey(); char getOper(); void result(float result); LiquidCrystal lcd(13, 12, 11, 10, 9, 8); int row[4]={4, 5, 6, 7}; int col[4]={1, 2, 3, 4}; int key1; char oper; int key2; void setup() { lcd.begin(16, 2); for(int i=0;i<=3;i++) { pinMode(row[i], OUTPUT); pinMode(col[i], INPUT); } for(int j=0;j<=3;j++) digitalWrite(col[j], HIGH); for(int k=0;k<=3;k++) digitalWrite(row[k], HIGH); lcd.print("CALCULATOR!!!!"); delay(4000); lcd.clear(); lcd.setCursor(0, 0); } void loop() { lcd.clear(); lcd.setCursor(0, 0 ); lcd.print("ENTER 1 NO ="); key1=getKey(); delay(3000); lcd.clear(); lcd.setCursor(0, 0); lcd.print("ENTER 2 NO ="); key2=getKey(); delay(3000); lcd.clear(); lcd.setCursor(0, 0); lcd.print("OPERATOR ="); oper=getOper(); delay(3000); lcd.clear(); lcd.setCursor(0, 0); lcd.print("RESULT ="); switch(oper) { case '+': result((float)key1+key2); break; case '-': result((float)key1-key2); break; case '/': result((float)key1/key2); break; case '*': result((float)key1*key2); break; case '^': result((float)pow(key1,key2)+1); break; case '%': result(key1%key2); break; } } int getKey() { int key=13; int Readrow,Readcol; while(key!=1 && key!=2 && key!=3 && key!=4 && key!=5 && key!=6 && key!=7 && key!=8 && key!=9 && key!=0) { digitalWrite(row[0], LOW); Readrow=digitalRead(row[0]); Readcol=digitalRead(col[0]); if((Readrow==LOW) && (Readcol==LOW)) { lcd.print("1"); digitalWrite(row[0], HIGH); return key=1; } digitalWrite(row[0], HIGH); digitalWrite(row[0], LOW); Readrow=digitalRead(row[0]); Readcol=digitalRead(col[1]); if( (Readrow==LOW )&&( Readcol==LOW)) { lcd.print("2"); digitalWrite(row[0], HIGH); return key=2; } digitalWrite(row[0], HIGH); digitalWrite(row[0], LOW); Readrow=digitalRead(row[0]); Readcol=digitalRead(col[2]); if( (Readrow==LOW) &&( Readcol==LOW)) { lcd.print("3"); digitalWrite(row[0], HIGH); return key=3; } digitalWrite(row[0], HIGH); digitalWrite(row[0], LOW); Readrow=digitalRead(row[0]); Readcol=digitalRead(col[3]); if(( Readrow==LOW )&&( Readcol==LOW)) { lcd.print("4"); digitalWrite(row[0], HIGH); return key=4; } digitalWrite(row[0], HIGH); for(int i=0;i<=3;i++) { digitalWrite(row[1], LOW); Readrow=digitalRead(row[1]); Readcol=digitalRead(col[i]); if( (Readrow==LOW) && (Readcol==LOW)) { lcd.print(4+(i+1)); digitalWrite(row[1], HIGH); return key=(4+(i+1)); break; } } digitalWrite(row[1], HIGH); digitalWrite(row[2], LOW); Readrow=digitalRead(row[2]); Readcol=digitalRead(col[0]); if( (Readrow==LOW )&& (Readcol==LOW)) { lcd.print("9"); digitalWrite(row[2], HIGH); return key=9; } digitalWrite(row[2], HIGH); digitalWrite(row[2], LOW); Readrow=digitalRead(row[2]); Readcol=digitalRead(col[1]); if( (Readrow==LOW) &&( Readcol==LOW)) { lcd.print("0"); digitalWrite(row[2], HIGH); return key=0; } digitalWrite(row[2], HIGH); key=13; }//While loop ends return 0; }//GetKey function ends char getOper() { int Readrow,Readcol; char key='l'; while(key!='+' && key!='-' && key!='/' && key!='*' && key!='^' && key!='%' ) { digitalWrite(row[2], LOW); Readrow=digitalRead(row[2]); Readcol=digitalRead(col[2]); if( (Readrow==LOW) &&( Readcol==LOW)) { lcd.print("+"); digitalWrite(row[2], HIGH); return key='+'; } digitalWrite(row[2], HIGH); digitalWrite(row[2], LOW); Readrow=digitalRead(row[2]); Readcol=digitalRead(col[3]); if( (Readrow==LOW) && (Readcol==LOW)) { lcd.print("-"); digitalWrite(row[2], HIGH); return key='-'; } digitalWrite(row[2], HIGH); digitalWrite(row[3], LOW); Readrow=digitalRead(row[3]); Readcol=digitalRead(col[0]); if( (Readrow==LOW) && (Readcol==LOW)) { lcd.print("/"); digitalWrite(row[3], HIGH); return key='/'; } digitalWrite(row[3], HIGH); digitalWrite(row[3], LOW); Readrow=digitalRead(row[3]); Readcol=digitalRead(col[1]); if( (Readrow==LOW) && (Readcol==LOW)) { lcd.print("*"); digitalWrite(row[3], HIGH); return key='*'; } digitalWrite(row[3], HIGH); digitalWrite(row[3], LOW); Readrow=digitalRead(row[3]); Readcol=digitalRead(col[2]); if( (Readrow==LOW) && (Readcol==LOW)) { lcd.print("^"); digitalWrite(row[3], HIGH); return key='^'; } digitalWrite(row[3], HIGH); digitalWrite(row[3], LOW); Readrow=digitalRead(row[3]); Readcol=digitalRead(col[3]); if( (Readrow==LOW) && (Readcol==LOW)) { lcd.print("%"); digitalWrite(row[3], HIGH); return key='%'; } digitalWrite(row[3], HIGH); key='c'; }//while loop ends return '\0'; }//getOper function ends void result(float result) { int unitvalue,tenvalue,decimal; float value=result; if(result<0.0) { lcd.print("-"); value=result*(-1); } if(value>10.0) { tenvalue=(int)value/10; lcd.print(tenvalue); } unitvalue=(int)value%10; lcd.print(unitvalue); lcd.print("."); decimal=(int)((int)(value*10)%10); lcd.print(decimal); delay(5000); lcd.clear(); lcd.setCursor(0, 0); }

After we finished making the series, the LCD did not display anything. It only shone blue light even though we already tried to set the potentiometer. Because Alif had to go to Friday Prayers, he went first and we tried our best to make the LCD able to display anything. Yet, nothing is happen. So we ask other friends of us and end up with a conclusion that we need to solder the LCD to pin head. I have a solder from my last year project but I did not bring it at that time. Since we had to join a tutor too, we decided to postpone it to unknown time since we just have no time anymore and....examination was only in days.

Yet, finally we decided to finish it on the next day, Saturday. So I was coming to campus on Saturday morning. 11 a.m still morning right? I brought my solder this time. Believe me, I am great in soldering because I already learnt it since Junior High School. The only thing that I like from this electronic thing is soldering. Nothing else.

We thought everything will be okay after soldering the LCD to pin heads. After rebuilding the series, we uploaded the source code to our Arduino but even the LCD was all blank. There was no blue light that shone. The keypad did not work too. I was really confuse that I thought I soldered it wrong. But...what can be wrong in soldering something? You only put the tin and solder it there. What can be wrong that the LCD did not shine at all? I tried to check the ground and there was pin in wrong pin indeed. My fault, again. Since I did not understand the rest of the series, Alif and Fanni checked it and they thought everything has already been in right place. We tried to check every jumper cables too but they were fine. So we concluded that our LCD might already been explode inside and our keypad had already broken too. Then, Fanni and I tried to look for friends who was in campus and brought their component. We would like to borrow their LCD and keypad. Yet there was no one. In that confusion, Alif called me to tell that the series had already worked. I was like.....how did he do that? at that time. So I back to the place where we work and found out that the LCD displayed something on the screen. But there was no the blue light. It turned out that the back light was not connected to the Arduino. Alif and Fanni connected it and it worked! WOW! I was amazed too. I have no idea how it finally was able to work. When I asked Alif what did he does, he answered that he only rebuilding the series. Since like our first series was wrong. Phew! I can not understand breadboard. So hard to understand it tho. But however, we finally made it!

For a better documentation, I give you our video so you know that we really did it. Yeay!

As a closing, here is our ga-jelas photo since we are in ga-jelas week right now(?) Please wish us the best to be able to pass this examination week well. I guess I already failed one *sob*

have a good week!

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Eka Theresia Kartika Suri