LCD RGB Display Off
When the programs exits, notice that the LCD still display the blinking cursor as well the message.. as a challenge write a method that turns off the LCD.
Answer:
void turnOffLCD(I2CCONTEXT *lcd)
{
writeByteRegister(lcd->file, 0x00, LCD_DISPLAYCONTROL );
writeByteRegister(lcd->file, 0x00, LCD_CLEARDISPLAY );
}By now the whole code should look like this...
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/i2c-dev-user.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdbool.h>
#include <inttypes.h>
#define RGB_SLAVE 0x62
#define LCD_SLAVE 0x3E
#define BUS 0x06
#define REG_RED 0x04 // pwm2
#define REG_GREEN 0x03 // pwm1
#define REG_BLUE 0x02 // pwm0
#define REG_MODE1 0x00
#define REG_MODE2 0x01
#define REG_OUTPUT 0x08
// commands
#define LCD_CLEARDISPLAY 0x01
#define LCD_RETURNHOME 0x02
#define LCD_ENTRYMODESET 0x04
#define LCD_DISPLAYCONTROL 0x08
#define LCD_CURSORSHIFT 0x10
#define LCD_FUNCTIONSET 0x20
#define LCD_SETCGRAMADDR 0x40
#define LCD_SETDDRAMADDR 0x80
// flags for display entry mode
#define LCD_ENTRYRIGHT 0x00
#define LCD_ENTRYLEFT 0x02
#define LCD_ENTRYSHIFTINCREMENT 0x01
#define LCD_ENTRYSHIFTDECREMENT 0x00
// flags for display on/off control
#define LCD_DISPLAYON 0x04
#define LCD_DISPLAYOFF 0x00
#define LCD_CURSORON 0x02
#define LCD_CURSOROFF 0x00
#define LCD_BLINKON 0x01
#define LCD_BLINKOFF 0x00
// flags for display/cursor shift
#define LCD_DISPLAYMOVE 0x08
#define LCD_CURSORMOVE 0x00
#define LCD_MOVERIGHT 0x04
#define LCD_MOVELEFT 0x00
// flags for function set
#define LCD_8BITMODE 0x10
#define LCD_4BITMODE 0x00
#define LCD_2LINE 0x18
#define LCD_5x8DOTS 0x00
//////////////////////////////
typedef struct
{
int addr; //i2c address of device
int file; //reprsents a place to do the i2c read & write
int adapter_nr; //the bus number of the device
char filename[20]; //the name of the device
}I2CCONTEXT;
I2CCONTEXT lcd;
I2CCONTEXT rgb;
int initContext(I2CCONTEXT *ctx, int addr_,int bus)
{
ctx->addr = addr_;
ctx->adapter_nr = bus;
snprintf(ctx->filename, 19, "/dev/i2c-%d", ctx->adapter_nr);
ctx->file = open(ctx->filename, O_RDWR);
if (ctx->file < 0)
{
/* ERROR HANDLING; you can check errno 2 c what went wrong */
printf("Error ocurred @ opening BUS: (errno:%d) %s\n",
errno,
strerror(errno));
return -errno;
}
if (ioctl(ctx->file, I2C_SLAVE, ctx->addr) < 0)
{
/* ERROR HANDLING; you can check errno 2 c what went wrong */
printf("Error ocurred @ accessing slave: (errno:%d) %s\n",
errno,
strerror(errno));
return -errno;
}
}
__s32 writeWordRegister(int file, __u8 command, __u16 value)
{
__s32 res = -1;
res = i2c_smbus_write_word_data(file, command, value);
if (res < 0)
{
/* ERROR HANDLING: i2c transaction failed */
printf("Error writing reg: 0x%x, (errno:%d),%s",
command,errno,strerror(errno));
}
return res;
}
__s32 readWordRegister(int r, int file)
{
/* Using SMBus commands */
__u8 reg = r; /* Device register to access */
__s32 res = -1;
char buf[10];
res = i2c_smbus_read_word_data(file, reg);
if (res < 0)
{
/* ERROR HANDLING: i2c transaction failed */
printf("Error reading reg: 0x%x, (errno:%d),%s",
reg,errno,strerror(errno));
}
/*
else
{
printf("result: 0x%x\n",res);
}
*/
return res;
}
__s32 writeByteRegister(int file, __u8 register_, __u8 value)
{
__s32 res = -1;
res = i2c_smbus_write_byte_data(file, register_, value);
if (res < 0)
{
/* ERROR HANDLING: i2c transaction failed */
printf("Error writing byte, (errno:%d),%s\n",errno,
strerror(errno));
}
}
__s32 readRegister(int register_, int file)
{
__u8 reg = register_;
__s32 res = -1;
char buf[10];
res = i2c_smbus_read_word_data(file, reg);
if (res < 0)
{
/* ERROR HANDLING: i2c transaction failed */
printf("Error reading reg: 0x%x, (errno:%d),%s",
reg,errno,strerror(errno));
}
return res;
}
void setRGBColor(I2CCONTEXT *rgb, int r, int g, int b)
{
writeByteRegister(rgb->file, REG_RED, r);
writeByteRegister(rgb->file, REG_GREEN, g);
writeByteRegister(rgb->file, REG_BLUE, b);
}
void initRGB(I2CCONTEXT *rgb)
{
// backlight init
writeByteRegister(rgb->file, REG_MODE1, 0);
// set LEDs controllable by both PWM and GRPPWM registers
writeByteRegister(rgb->file, REG_OUTPUT, 0xFF);
// set MODE2 values
writeByteRegister(rgb->file, REG_MODE2, 0x20);
// set the baklight Color to white :)
setRGBColor(rgb, 0xFF, 0xFF, 0xFF);
}
void turnOffRGB(I2CCONTEXT *rgb)
{
setRGBColor(rgb, 0x00, 0x00, 0x00);
}
void initLCD(I2CCONTEXT *lcd)
{
writeByteRegister(lcd->file, 0x00, LCD_FUNCTIONSET | LCD_2LINE );
usleep(100);
writeByteRegister(lcd->file, 0x00,LCD_DISPLAYCONTROL | LCD_DISPLAYON | LCD_CURSORON | LCD_BLINKOFF );
usleep(100);
writeByteRegister(lcd->file, 0x00, LCD_CLEARDISPLAY );
usleep(4000);
writeByteRegister(lcd->file, 0x00,LCD_ENTRYMODESET | LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT );
}
void turnOffLCD(I2CCONTEXT *lcd)
{
writeByteRegister(lcd->file, 0x00, LCD_DISPLAYCONTROL );
writeByteRegister(lcd->file, 0x00, LCD_CLEARDISPLAY );
}
void clearLCD(I2CCONTEXT *lcd)
{
writeByteRegister(lcd->file, 0x00, LCD_CLEARDISPLAY );
}
void writeToLCD(I2CCONTEXT *lcd, char *c)
{
//writeByteRegister(lcd->file, 0x80, 0x48);
//usleep(4000);
uint ascii_val=0;
int i;
int s = strlen(c);
for(i = 0 ; i < s; i++)
{
ascii_val = toascii(c[i]);
writeByteRegister(lcd->file, 0x40, ascii_val);
}
}
int main()
{
//Grove LCD has two devices one that drives LCD
//and a second that drives RGB
initContext(&rgb, RGB_SLAVE , BUS);
initContext(&lcd, LCD_SLAVE , BUS);
////////////////////////////////////////////////////////////
//init RGB device & set White color
initLCD(&lcd);
initRGB(&rgb);
writeToLCD(&lcd, ":) HOLO!");
/*sleep for 5 secs before turning off*/
sleep(5);
/*turn off RGB LEDS*/
turnOffRGB(&rgb);
turnOffLCD(&lcd);
printf("\nDONE!\n");
return 0;
}Last updated