grove_lcd/grove_lcd.c

#include <errno.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdint.h>
#include <linux/i2c-dev.h>
#include <i2c/smbus.h>
#include <getopt.h>

//Device specific information. (Perhaps better as command options or config file)
#define MPC9808_BUS     "/dev/i2c-2"
#define DISPLAY_RGB_ADDR 0x62
#define DISPLAY_TEXT_ADDR 0x3e

void init_display(int file) {
    // Function set 0010 1000 // 2 line mode and 5x8
	i2c_smbus_write_byte_data(file, 0x00, 0x28);
    // Display on/off control 0000 1110 // Diplay on; cursor off; blink off
	i2c_smbus_write_byte_data(file, 0x00, 0x0C);
    // Clear display
	i2c_smbus_write_byte_data(file, 0x00, 0x01);
	i2c_smbus_write_byte_data(file, 0x00, 0x06);
    
	i2c_smbus_write_byte_data(file, 0x00, 0x02);
	i2c_smbus_write_byte_data(file, 0x00, 0x84);
}

void clear_display(int file) {
	i2c_smbus_write_byte_data(file, 0x00, 0x01);
}

void write_to_display_xy(int file, int x, int y, char* message) {
	int line;
	if(x > 16) {
        fprintf(stderr, "Invalid line position");
		return;
    }
	if(y == 1)
		line = 0x80; // first line (1000 0000 to 1000 1111 possible on 16 characters line) = 0x80 to 0x8f
	else if(y == 2)
		line = 0xC0; // second  line (1100 0000 to 1100 1111 possible on 16 characters line) = 0xC0 to 0xCf
	else {
        fprintf(stderr, "Invalid line position");
		return;
    }
	line += x-1;

	i2c_smbus_write_byte_data(file, 0x00, line);
	while (*message != 0) {
		i2c_smbus_write_byte_data(file, 0x40, *message);
		message++;
	}
}

int i2c_init(char *bus, unsigned int address) {
        int file;

        file = open(bus, O_RDWR);
        if (file < 0) { // If error
                fprintf(stderr, "ERROR: opening %s - %s\n", bus, strerror(errno));
                exit(1);
        }

        if (ioctl(file, I2C_SLAVE, address) == -1 ) { // If error
             fprintf(stderr, "ERROR: setting  address %d on i2c bus %s with ioctl() - %s", address, bus, strerror(errno) );
             exit(1);
        }
        return(file);
}

void set_backlight(int r, int g, int b) {
	int file;
	file = i2c_init(MPC9808_BUS, DISPLAY_RGB_ADDR);
	i2c_smbus_write_byte_data(file, 0, 0);
	i2c_smbus_write_byte_data(file, 1, 0);
	i2c_smbus_write_byte_data(file, 0x08,0xaa);

	i2c_smbus_write_byte_data(file, 4, r);
	i2c_smbus_write_byte_data(file, 3, g);
	i2c_smbus_write_byte_data(file, 2, b);
}

int main(int argc, char *argv[]) {
    int l1p = 1;
    int l2p = 1;
    int option;

    while ((option = getopt (argc, argv, "l1:l2:")) != -1) {
       switch (option) {
        case '1':
           l1p = atoi(optarg);
           break;
        case '2':
            l2p = atoi(optarg);
            break;
        default:
            fprintf(stderr, "Usage: %s -l1 <value> -l2 <value>\n", argv[0]);
            exit(EXIT_FAILURE);
        }
    }

    printf("l1p = %d, l2p = %d\n", l1p, l2p);

	int file;
    set_backlight(1, 0, 0);
	file = i2c_init(MPC9808_BUS, DISPLAY_TEXT_ADDR);
	init_display(file);
    write_to_display_xy(file, l1p, 1, "Mercantec");
    write_to_display_xy(file, l2p, 2, "Mercantec");
	return 0;
}