Example program using Gryphon’s LCD and Keypad

This is an example of how to write a program to display information on Gryphon's LCD screen and how to use the keypads. See lcdmenu.htm for directions on how to load programs to run from Gryphon's menu system.

/* 
glcd.c: Demonstration of LCD/keypad use on Gryphon 
20010418/js 

lcd is accessed via node /gryphon/dev/glcd 
keypad is accessed via node /gryphon/dev/gkeypad 

The LCD device recognizes the following printf-like special 
control character sequences: 

        \n new line 
        \f clear screen 
        \b move cursor left (but never up) one position 
        \r return cursor to home position (0,0) 

        mvXY move cursor to position X Y e.g.: 
        mv\011\001 moves cursor to the second line down, and 9 chars across 
        mb blinking cursor 
        mc normal cursor 
        mn no cursor 
        mf turn display off (reversed by any of above 3 commands) 

where  is the escape character (dec. 27, oct. \033, hex 0x1b) 
*/ 

#define L_ARROW 0x7f 
#define R_ARROW 0x7e 


#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <sys/file.h> 


/* Keypad bit definitions: */ 
#define UP 0x01 
#define DOWN 0x02 
#define LEFT 0x04 
#define RIGHT 0x08 

int main(void) 
{ 
        int lcd,key,exit; 
        unsigned char buf[256]; 
        unsigned char kp; 


        /* Open the LCD device */ 
        if (!(lcd = open ("/gryphon/dev/glcd", O_RDWR))) 
        { 
                printf ("\nCouldn't open lcd file.\n"); 
                return(-1); 
        } 


        /* Open the keypad device */ 

        if (!(key = open ("/gryphon/dev/gkeypad", O_RDWR))) 
        { 
                printf ("\nCouldn't open keypad file.\n"); 
                return(-1); 
        } 

        /* Clear LCD, print banner on LCD */ 
        sprintf(buf,"\f Gryphon LCD/Key Test\n--[%c and %c to exit]--",L_ARROW,R_ARROW); 
        write(lcd,buf,strlen(buf)); 

        /* Read keypad, print message until exit 
        condition occurs (L and R keys simultaneously) */ 
        exit=0; 
        do { 
                read(key,&kp,1); /* Get current key state */ 
                kp&=0x0f; /* Upper 4 bits are undefined */ 
                switch(kp) 
                { 
                        case UP: /* UP key pressed? */ 
                                sprintf(buf,"\033mv\001\002 UP key pressed "); 
                                break; 
                        case DOWN: /* Down key pressed? */ 
                                sprintf(buf,"\033mv\001\002 DOWN key pressed "); 
                                break; 
                        case LEFT: /* Left key pressed? */ 
                                sprintf(buf,"\033mv\001\002 LEFT key pressed "); 
                                break; 
                        case RIGHT: /* Right key pressed? */ 
                                sprintf(buf,"\033mv\001\002RIGHT key pressed "); 
                                break; 
                        case LEFT|RIGHT: /* Both L and R keys? (exit) */ 
                                exit=1; 
                                sprintf(buf,"\033mv\001\002Exiting demo program"); 
                        default: 
                                break; 
                } 

                /* If key pressed, print a message on LCD */ 
                if(kp) write(lcd,buf,strlen(buf)); 
        } while(!exit); 

        /* Close files and exit */ 
        close(lcd); 
        close(key); 
        return 0; 
}
This document was obtained from:
Dearborn Group, Inc.
(248) 488-2080
dg@dgtech.com
http://www.dgtech.com