Interfacing an LCD

Lcd

a 16 pin lcd have following pin connection

Printing Functions

Now once the connections have been made, we are ready to display something on our screenSome of the general LCD functions which you must know are:

lcd_clear()

Clears the lcd. Remember! Call this function before the while(1) loop, otherwise you won’t be able to see anything!

lcd_gotoxy(x,y)

Place the cursor at coordinates (x,y) and start writing from there. The first coordinate is (0,0). Hence, x ranges from 0 to 15 and y from 0 to 1 in our LCD.

Example: you want to display something starting from the 5th character in second line, then the function would be

lcd_gotoxy(5,1);

lcd_putchar(char c)

To display a single character.

E.g.,

lcd_putchar(‘H’);

lcd_putsf(constant string)

To display a constant string.

Eg,

lcd_putsf(“IIT Kanpur”);

lcd_puts(char arr)

To display a variable string, ie an array of characters (data type char) in C language .

 e.g., You have an array char c[10] which keeps on changing. Then to display it, the function would be called as

lcd_puts(c);

Now we have seen that only characters or strings (constant or variable) can be displayed on the LCD. But quite often we have to display values of numeric variables, which is not possible directly. Hence we need to first convert that numeric value to a string and then display it. For e.g., if we have a variable of type integer, say int k, and we need to display the value of k (which changes every now and then, 200 now and 250 after a second... and so on). For this, we use the C functions itoa() and ftoa(), but remember to include the header file <stdlib.h> to use these C functions.

 itoa(int val, char arr[])

It stores the value of integer val in the character array arr. E.g., we have already defined int i and char c[20], then

itoa(i,c);

lcd_puts(c);

Similarly we have

ftoa(float val, char decimal_places, char arr[])

It stores the value of floating variable f in the character array arr with the number of decimal places as specified by second parameter. E.g., we have already defined float f and char c[20], then

ftoa(f,4,c); // till 4 decimal places

lcd_puts(c);

Now we are ready to display anything we want on our LCD. Just try out something which you would like to see glowing on it!

header file required : #include<lcd.h>   //but it is not required as it is already applied by cvavr by selecting lcd

HOW TO SELECT LCD:

get started with lcd on cvavr