Hello,
I am still fairly new to MCU and experimenting with different projects. Right now I am working on a LCD project. Now I am not too sure on how to enable the backlight, I am using an ARM 2103 with this LCD panel
LCD Display - LCD16x2BL
www.futurlec.com/LED/LCD16x2BL.shtml

Interface Pin Connections
Symbol Level Function No. Symbol Level Function
1 Vss GND(OV) 9 DB 2 H/L Data Bit 2
2 VDD VCC(+5V±5%) 10 DB 3 H/L Data Bit 3
3 Vo Contrast ADJ 11 DB 4 H/L Data Bit 4
4 RS H/L Register Select 12 DB 5 H/L Data Bit 5
5 R/W H/L Read/Write 13 DB 6 H/L Data Bit 6
6 E H.H-L Enable Signal 14 DB 7 H/L Data Bit 7
7 DB 0 H/L Data Bit 0 15 A BKL+ Backlght +
8 DB 1 H/L Data Bit 1 16 K BKL- Backlght -
And here is the code I am implementing

#include // LPC2103 MPU Register
// Define LCD PinIO Mask
#define LCD_EN 0x00020000 // P0.17(0000 0000 0000 00x0 0000 0000 0000 0000)
#define LCD_RW 0x00040000 // P0.18(0000 0000 0000 0x00 0000 0000 0000 0000)
#define LCD_RS 0x00080000 // P0.19(0000 0000 0000 x000 0000 0000 0000 0000)
#define LCD_D4 0x00100000 // P0.20(0000 0000 000x 0000 0000 0000 0000 0000)
#define LCD_D5 0x00200000 // P0.21(0000 0000 00x0 0000 0000 0000 0000 0000)
#define LCD_D6 0x00400000 // P0.22(0000 0000 0x00 0000 0000 0000 0000 0000)
#define LCD_D7 0x00800000 // P0.23(0000 0000 x000 0000 0000 0000 0000 0000)

#define LCD_DATA (LCD_D7|LCD_D6|LCD_D5|LCD_D4)
#define LCD_IOALL (LCD_D7|LCD_D6|LCD_D5|LCD_D4|LCD_RS|LCD_RW|LCD_EN)

#define lcd_rs_set() IOSET = LCD_RS // RS = 1 (Select Instruction)
#define lcd_rs_clr() IOCLR = LCD_RS // RS = 0 (Select Data)
#define lcd_rw_set() IOSET = LCD_RW // RW = 1 (Read)
#define lcd_rw_clr() IOCLR = LCD_RW // RW = 0 (Write)
#define lcd_en_set() IOSET = LCD_EN // EN = 1 (Enable)
#define lcd_en_clr() IOCLR = LCD_EN // EN = 0 (Disable)

// 0000 0000 xxxx xxx0 0000 0000 0000 0000
#define lcd_dir_write() IODIR |= 0x00FE0000 // LCD Data Bus = Write
#define lcd_dir_read() IODIR &= 0xFF0EFFFF // LCD Data Bus = Read

#define lcd_clear() lcd_write_control(0x01) // Clear Display
#define lcd_cursor_home() lcd_write_control(0x02) // Set Cursor = 0
#define lcd_display_on() lcd_write_control(0x0E)// LCD Display Enable
#define lcd_display_off() lcd_write_control(0x08)// LCD Display Disable
#define lcd_cursor_blink() lcd_write_control(0x0F)// Set Cursor = Blink
#define lcd_cursor_on() lcd_write_control(0x0E)// Enable LCD Cursor
#define lcd_cursor_off() lcd_write_control(0x0C)// Disable LCD Cursor
#define lcd_cursor_left() lcd_write_control(0x10)// Shift Left Cursor
#define lcd_cursor_right() lcd_write_control(0x14)// Shift Right Cursor
#define lcd_display_sleft()lcd_write_control(0x18)// Shift Left Display
#define lcd_display_sright()lcd_write_control(0x1C)// Shift Right Display

/* pototype section */
void lcd_init(); // Initial LCD
void lcd_out_data4(unsigned char); // Strobe 4-Bit Data to LCD
void lcd_write_byte(unsigned char); // Write 1 Byte Data to LCD
void lcd_write_control(unsigned char); // Write Instruction
void lcd_write_ascii(unsigned char); // Write LCD Display(ASCII)
void goto_cursor(unsigned char); // Set Position Cursor LCD
void lcd_print(unsigned char*); // Print Display to LCD
char busy_lcd(void); // Read Busy LCD Status
void enable_lcd(void); // Enable Pulse
void delay(unsigned long int); // Delay Function

/* Main Program Start Here */
int main(void)
{
lcd_init(); // Initial LCD

// Loop Print Message to LCD16 x 2 //
while(1) / Loop Continue
{

goto_cursor(0x00); Set Cursor Line-1
lcd_print(" Team Pegasus "); //Display LCD Line-1
goto_cursor(0x40);
lcd_print(" Game Night ");
delay(10000000); // Display Delay

goto_cursor(0x00);
lcd_print(" ");
goto_cursor(0x40);
lcd_print(" ");
goto_cursor(0x00); // Set Cursor Line-1
lcd_print("PongBot 0.5 "); // Display LCD Line-1
delay(10000000); // Display Delay
goto_cursor(0x40); // Set Cursor = Line-2
lcd_print("I will destroy!!"); // Display LCD Line-2
delay(5000000); // Display Delay
lcd_clear();
delay(5000000); // Display Delay
}

}

/****************************/
/* Strobe 4-Bit Data to LCD */
/****************************/
void lcd_out_data4(unsigned char val)
{
IOCLR = (LCD_DATA); // Reset 4-Bit Pin Data
IOSET = (val<<20); // 0000:0000:dddd:RS,RW,EN,0:0000:0000:0000:0000
}

/****************************/
/* Write Data 1 Byte to LCD */
/****************************/
void lcd_write_byte(unsigned char val)
{
lcd_out_data4((val>>4)&0x0F); // Strobe 4-Bit High-Nibble to LCD
enable_lcd(); // Enable Pulse

lcd_out_data4(val&0x0F);// Strobe 4-Bit Low-Nibble to LCD
enable_lcd(); // Enable Pulse

while(busy_lcd()); // Wait LCD Execute Complete
}

/****************************/
/* Write Instruction to LCD */
/****************************/
void lcd_write_control(unsigned char val)
{
lcd_rs_clr(); // RS = 0 = Instruction Select
lcd_write_byte(val); // Strobe Command Byte
}

/****************************/
/* Write Data(ASCII) to LCD */
/****************************/
void lcd_write_ascii(unsigned char c)
{
lcd_rs_set(); // RS = 1 = Data Select
lcd_write_byte(c); // Strobe 1 Byte to LCD
}

/*******************************/
/* Initial 4-Bit LCD Interface */
/*******************************/
void lcd_init()
{
unsigned int i; // Delay Count

PINSEL0 = 0x00000000; // GPIO0 = I/O Function
PINSEL1 = 0x00000000;
IODIR = 0x00FE0000; // P0[23..17] = Output
for (i=0;i<50000;i++); // Power-On Delay (15 mS)

IOCLR = (LCD_IOALL); // Reset (RS,RW,EN,4-Bit Data) Pin
IOSET = (LCD_D5|LCD_D4);//0000:0000:(0,RS,RW,EN:0011):0000:0000:0000:0000
enable_lcd(); // Enable Pulse
for (i=0;i<10000;i++); // Delay 4.1mS

IOCLR = (LCD_IOALL); // Reset (RS,RW,EN,4-Bit Data) Pin
IOSET = (LCD_D5|LCD_D4);//0000:0000:(0,RS,RW,EN:0011):0000:0000:0000:0000
enable_lcd(); // Enable Pulse
for (i=0;i<100;i++); // delay 100uS

IOCLR = (LCD_IOALL); // Reset (RS,RW,EN,4-Bit Data) Pin
IOSET = (LCD_D5|LCD_D4);//0000:0000:(0,RS,RW,EN:0011):0000:0000:0000:0000
enable_lcd(); // Enable Pulse
while(busy_lcd()); // Wait LCD Execute Complete

IOCLR = (LCD_IOALL); // Reset (RS,RW,EN,4-Bit Data) Pin
IOSET = (LCD_D5); // 0000:0000:(0,RS,RW,EN:0011):0000:0000:0000:0000
enable_lcd(); // Enable Pulse
while(busy_lcd()); // Wait LCD Execute Complete

lcd_write_control(0x28);// Function Set (DL=0 4-Bit,N=1 2 Line,F=0 5X7)
lcd_write_control(0x0C);// Display on/off Control (Entry Display,Cursor off,Cursor not Blink)
lcd_write_control(0x06);// Entry Mode Set (I/D=1 Increment,S=0 Cursor Shift)
lcd_write_control(0x01);// Clear Display (Clear Display,Set DD RAM Address=0)
for (i=0;i<100000;i++); // Wait Command Ready
}

/***************************/
/* Set LCD Position Cursor */
/***************************/
void goto_cursor(unsigned char i)
{
i |= 0x80; // Set DD-RAM Address Command
lcd_write_control(i);
}

/************************************/
/* Print Display Data(ASCII) to LCD */
/************************************/
void lcd_print(unsigned char* str)
{
int i;

for (i=0;i<16 && str[i]!=0;i++) // 16 Character Print
{
lcd_write_ascii(str[i]); // Print Byte to LCD
}
}

/******************/
/* Wait LCD Ready */
/******************/

char busy_lcd(void)
{
unsigned long busy_status; // Busy Status Read
unsigned int i; // Delay Count

lcd_dir_read(); // LCD Data Bus = Read
lcd_rs_clr(); // Instruction Select
lcd_rw_set(); // Read Direction
lcd_en_set(); // Start Read Busy

for (i=0;i<100;i++); // Delay Before Read
busy_status = (IOPIN & 0x00800000); // Read LCD Data(0000:0000:dddd:RS,RW,EN,0:0000:0000:0000:0000)

if(busy_status == 0x00800000) // Read & Check Busy Flag
{
lcd_en_clr(); // Disable Read
lcd_rw_clr(); // Default = Write Direction
lcd_dir_write(); // LCD Data Bus = Write
return 1; // LCD Busy Status
}
else
{
lcd_en_clr(); // Disable Read
lcd_rw_clr(); // Default = Write Direction
lcd_dir_write(); // LCD Data Bus = Write
return 0; // LCD Ready Status
}
}
/***********************/
/* Enable Pulse to LCD */
/***********************/
void enable_lcd(void) // Enable Pulse
{
unsigned int i; // Delay Count
lcd_en_set(); // Enable ON
for (i=0;i<50;i++);
lcd_en_clr(); // Enable OFF
}

/***********************/
/* Delay Time Function */
/* 1-4294967296 */
/***********************/
void delay(unsigned long int count1)
{
while(count1 > 0) {count1--;} // Loop Decrease Counter
} Start a New Thread

--- In l..., shawnzyoo@... wrote:
>
> Hello,
> I am still fairly new to MCU and experimenting with different
projects. Right now I am working on a LCD project. Now I am not too
sure on how to enable the backlight, I am using an ARM 2103 with this
LCD panel
> LCD Display - LCD16x2BL
> www.futurlec.com/LED/LCD16x2BL.shtml

Ordinarily, the controller doesn't have anything to do with the
backlight. There are displays where the controller does control the
intensity like the Matrix Orbital LK204 but I don't think this one
those.

The problem is the WIDE variation in LED current depending on color. A
white backlight might require 20 mA and a yellow backlight might
require 120 mA. See this datasheet
http://www.jameco.com/Jameco/Products/ProdDS/658988.pdf page 2
Electrical Characteristics.

Note that it is up to the user to provide a current limiting resistor
for the LED. The value R is (Vsupply - Vf) / If

For the white LED at If = 20 mA, Vf = 3.4V, Vsupply = 5.0V, the value
would be 80 ohms.

For the yellow LED at If = 120 mA, Vf = 4.1V, Vsupply = 5.0V, the value
would be 7.5 ohms.

Connect the resistor as shown in the Block Diagram of the referenced
datasheet.

Unfortunately, there is no specification for the LED Vf and If values
for your display. You are on your own!

Richard Start a New Thread