[SOLVED] Convert Keypad Input Char Array into String To Compare with Predefined String

Nabil Fikri · Sep 7, 2015

Hello guys. Thank for stopping by here.
I made a PC based door lock keypad project. From the keypad, each key press will store a char to an array. After that, I want to convert the char array to string. The string will be send to PC to compare with the database there. The problem here is I cant find a way to convert the char array into string. I have done multiple trials but it the end it messed up the whole project. So, I need help from someone who have done this before.

Here is my full code. The code only works as stand alone door lock system. I can't find a way to send the string from here,

Code:

// Lcd module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;
// End Lcd module connections
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;

void beep_once();
void correct();
void wrong();
int scan_keypad();
void init();

char keypadPort at PORTD;
unsigned short kp;
unsigned int x = 6;

unsigned char password_count=0;
// Declare an array to stall the 6-digit key in password
unsigned char keyin_char[6];
// Declare an array to stall the 6-digit desired password
unsigned char stalled_char[6]={'1','2','3','4','5','6'};

void main(){
    IRCF2_bit = 1;       //internal oscillator
    IRCF1_bit = 1;
    IRCF0_bit = 0;
    INTSRC_bit = 1;
    PLLEN_bit = 0;
    
    TRISA = 0b0000000;   //0-red, 1-green, 2-relay, 3-buzzer
    PORTA = 0b0000000;
    
    TRISB = 0b0000000;   //lcd
    TRISC = 0b0000000;   //0-3 are row
    TRISD = 0b0000111;   //0-2 are column

    ANSELA = 0;          //set all port as digital port I/O
    ANSELB = 0;
    ANSELC = 0;
    ANSELD = 0;
    
    Keypad_Init();       //initialize keypad
    init();
    Lcd_Init();          //initialize Lcd
    Lcd_Cmd(_LCD_CLEAR);              //Clear display
    Lcd_Cmd(_LCD_CURSOR_OFF);         //Cursor off
    Lcd_Out(1,2,"Enter Password");      //Prompt user to insert password
    
    while(1){           //main program running continuously
        scan_keypad();

        if(password_count==6){
            password_count=0;
            //compare the keyin value with stalled value to test whether password is correct
            if((keyin_char[0]==stalled_char[0])&&(keyin_char[1]==stalled_char[1])&&
                (keyin_char[2]==stalled_char[2])&&(keyin_char[3]==stalled_char[3])&&
                (keyin_char[4]==stalled_char[4])&&(keyin_char[5]==stalled_char[5]))
                {
                    Lcd_Cmd(_LCD_CLEAR);
                    Lcd_Out(1,2,"Door Unlocked!");
                    Lcd_Out(2,3,"Welcome Back!");

                    PORTA.F2 = 1;
                    PORTA = 0b0000101;
                    correct();
                    
                    delay_ms(10000);    //door open for 10 seconds
                    PORTA = 0b0000000; //reset output
                    init();
                    x = 6;
                    continue;
                }
            else
                {
                    Lcd_Cmd(_LCD_CLEAR);
                    Lcd_Out(1,2,"Wrong Password!");
                    Lcd_Out(2,1,"Please Try Again");

                    PORTA = 0b0000010;
                    wrong();

                    delay_ms(1000);
                    PORTA = 0b0000000; //reset output
                    init();
                    x = 6;
                    continue;
                }
        }
    }
    Delay_ms(250);
}

int scan_keypad(){

    PORTC = 0b0001110;                //scan 1st row
    if(PORTD.F0==0){                  //1
    while(PORTD.F0==0)continue;
    kp = 49;
    keyin_char[password_count]='1';
    password_count+=1;
    Lcd_Chr(2,x,'1');
    beep_once();
    x++;
    }
    else if (PORTD.F1==0){            //2
    while(PORTD.F1==0)continue;
    kp = 50;
    keyin_char[password_count]='2';
    password_count+=1;
    Lcd_Chr(2,x,'2');
    beep_once();
    x++;
    }
    else if (PORTD.F2==0){            //3
    while(PORTD.F2==0)continue;
    kp = 51;
    keyin_char[password_count]='3';
    password_count+=1;
    Lcd_Chr(2,x,'3');
    beep_once();
    x++;
    }

    PORTC = 0b0001101;                //scan 2nd row
    if(PORTD.F0==0){                  //4
    while(PORTD.F0==0)continue;
    kp = 52;
    keyin_char[password_count]='4';
    password_count+=1;
    Lcd_Chr(2,x,'4');
    beep_once();
    x++;
    }
    else if (PORTD.F1==0){            //5
    while(PORTD.F1==0)continue;
    kp = 53;
    keyin_char[password_count]='5';
    password_count+=1;
    Lcd_Chr(2,x,'5');
    beep_once();
    x++;
    }
    else if (PORTD.F2==0){            //6
    while(PORTD.F2==0)continue;
    kp = 54;
    keyin_char[password_count]='6';
    password_count+=1;
    Lcd_Chr(2,x,'6');
    beep_once();
    x++;
    }

    PORTC = 0b0001011;                //scan 3rd row
    if(PORTD.F0==0){                  //7
    while(PORTD.F0==0)continue;
    kp = 55;
    keyin_char[password_count]='7';
    password_count+=1;
    Lcd_Chr(2,x,'7');
    beep_once();
    x++;
    }
    else if (PORTD.F1==0){            //8
    while(PORTD.F1==0)continue;
    kp = 56;
    keyin_char[password_count]='8';
    password_count+=1;
    Lcd_Chr(2,x,'8');
    beep_once();
    x++;
    }
    else if (PORTD.F2==0){            //9
    while(PORTD.F2==0)continue;
    kp = 57;
    keyin_char[password_count]='9';
    password_count+=1;
    Lcd_Chr(2,x,'9');
    beep_once();
    x++;
    }

    PORTC = 0b0000111;                //scan 4th row
    if(PORTD.F0==0){                  //*
    while(PORTD.F0==0)continue;
    kp = 42;
    keyin_char[password_count]='*';
    password_count+=1;
    Lcd_Chr(2,x,'*');
    beep_once();
    x++;
    }
    else if (PORTD.F1==0){            //0
    while(PORTD.F1==0)continue;
    kp = 48;
    keyin_char[password_count]='0';
    password_count+=1;
    Lcd_Chr(2,x,'0');
    beep_once();
    x++;
    }
    else if (PORTD.F2==0){            //#
    while(PORTD.F2==0)continue;
    kp = 35;
    keyin_char[password_count]='#';
    password_count+=1;
    Lcd_Chr(2,x,'#');
    beep_once();
    x++;
    }
    return x;
}

void beep_once(){
    PORTA.F3 = 1;
    Delay_ms(100);
    PORTA.F3 = 0;
    Delay_ms(100);
}

void correct(){
    PORTA.F1 = 1;
    PORTA.F3 = 1;
    Delay_ms(250);
    PORTA.F1 = 0;
    PORTA.F3 = 0;
    Delay_ms(250);
    PORTA.F1 = 1;
    PORTA.F3 = 1;
    Delay_ms(250);
    PORTA.F1 = 0;
    PORTA.F3 = 0;
    Delay_ms(250);
}

void wrong(){
    PORTA.F0 = 1;
    PORTA.F3 = 1;
    Delay_ms(250);
    PORTA.F0 = 0;
    PORTA.F3 = 0;
    Delay_ms(250);
    PORTA.F0 = 1;
    PORTA.F3 = 1;
    Delay_ms(250);
    PORTA.F0 = 0;
    PORTA.F3 = 0;
    Delay_ms(250);
    PORTA.F0 = 1;
    PORTA.F3 = 1;
    Delay_ms(250);
    PORTA.F0 = 0;
    PORTA.F3 = 0;
    Delay_ms(250);
}

void init(){
    Lcd_Init();
    Lcd_Cmd(_LCD_CLEAR);              //Clear display
    Lcd_Cmd(_LCD_CURSOR_OFF);         //Cursor off
    Lcd_Out(1,2,"Enter Password");      //Prompt user to insert password
}

Any help is really appreciated.

andre_luis · Sep 7, 2015

You had not mentioned what compiler are using, but if it contains builtin ANSI C libraries such as the "string.h", you can enjoy with many functions that performs string handling.

Nabil Fikri · Sep 7, 2015

I'm using MikroC Pro. Sorry I forgot to mention it.

andre_luis · Sep 7, 2015

Afaik, you could append the null char '/0' right before the last character to be sent.
Aren't you aware of the UART library of this compiler ?

I, assuming you're using a PIC core due to some registers on the code above.
https://www.mikroe.com/download/eng/documents/compilers/mikroc/pro/pic/help/uart_library.htm ?

Nabil Fikri · Sep 7, 2015

I want to convert the array here

Code:

unsigned char keyin_char[6];

to string first before I send it through UART.

For example,

Code:

unsigned char keyin_char[6]={'1','2','3','4','5','6'};

//then how to convert to 123456 and then send via UART?

I tried multiple references from other forum but it did not work. I dont know where is the problem

Duresh · Sep 7, 2015

try this,

Code:

unsigned char keyin_char[6];    // you can only store 5 characters in this arrray. Last char is the null terminator for string.
char *string_pointer = &keyin_char[0];

void main()
{
// your code...
//after you taking all the input from the keypad and before using "string_pointer" you need to add 

keyin_char[5] = NULL; // if "NULL" is not define then -> keyin_char[5] = '\0';

now you can use "string_pointer" where you need to get "keyin_char" as a string.

for safety you need to check whether the "string_pointer" is null right before use it.

Code:

if(string_pointer != NULL)
{
// because "string_pointer" is not null we can use it
}

Nabil Fikri · Sep 7, 2015

Finally it works. Here is the full code

Code:

unsigned char keyin_char[5];    
unsigned char keyin_string[6];
int i;

for(x=0;x<6;x++){
keyin_string[i]=keyin_char[i];
}

keyin_string[5]='\0';

Thanks again guys

pic.programmer · Sep 7, 2015

Instead of doing this

Code:

for(x=0;x<6;x++){
keyin_string[i]=keyin_char[i];
}

can you just do this

Code:

unsigned char keyin_char[5];    

keyin_char[5] = '\0';

Welcome to EDAboard.com

[SOLVED] Convert Keypad Input Char Array into String To Compare with Predefined String

Nabil Fikri

Newbie level 3

andre_luis

Super Moderator

Nabil Fikri

Newbie level 3

andre_luis

Super Moderator

Nabil Fikri

Nabil Fikri

Newbie level 3

Duresh

Junior Member level 3

Nabil Fikri

Nabil Fikri

Newbie level 3

pic.programmer

Advanced Member level 3

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