In the calls I made of the delay function above you will have noticed that there are no numbers. Instead I write things like:

lcd_delay ( PUTCH_DELAY) ;

This is so that I can make my code more readable and flexible. Rather than put numbers in the calls of delay I have used #defined values which the pre-processor will insert for me. I can then indicate what the delay is doing by using an appropriate name and also easily change the value of the number if I change to a faster PICmicro. On the right you can see all the #defined values used in the LCD code.

Note that I have also used #define to indicate bit numbers and masks for use in the code.

/*  masks for control bits         */

#define RSMASK 0x10
#define EBIT 0x05

/*  defined values for delays      */
/*  tested up to 20Mhz PICmicro    */
/*  standard write delay           */

#define PUTCH_DELAY 250

/* clear and cursor home take      */
/* longer - special delay for them */

#define CLEAR_DELAY 5000

/*  delay to let the LCD settle    */

#define POWER_UP_DELAY 10000

/*  delay to let the ports settle  */

#define BIT_DELAY 2