Help me fix this program code for LCD

[jannogale]

the problem that i faced in this programm is that the letter B not appearing on LCD.
I need a help plz.

#define LCD_rs P2_4
#define LCD_rw P2_5
#define LCD_e P2_6
#define LCD_data P2
void main (void)
{
void delay(void);
void LCD_init (void);
void LCD_Control(unsigned char);
void LCD_Data(unsigned char d);

LCD_init();
LCD_Data('B');

while(1)
{
LCD_Data('B');

}

void LCD_init (void)
{
LCD_Control(0x03);
LCD_Control(0x03);
LCD_Control(0x03);
LCD_Control(0x02);
LCD_Control(0x28);

}
void delay(void)
{
int i = 0;
for (i = 0; i < 1000; i++);

}


void LCD_Data(unsigned char d)
{
unsigned char Hbyte;
unsigned char Lbyte;
Lbyte = d & 0xf0;
Hbyte = (d >> 4) & 0x0f;

P2 = 0;
P2 = P2 | Hbyte;
P2 = P2 | 0x50; //E = 1
delay();
P2 = P2 & ~0x50; // E = 0
delay();

P2 = P2 | Lbyte;
P2 = P2 | 0x50;
delay();
P2 = P2 & ~0x50;
delay();

P2 = 0;
}
void LCD_Control(unsigned char d)
{
unsigned char Hbyte;
unsigned char Lbyte;
Lbyte = d & 0xf0;
Hbyte = (d >> 4) & 0x0f;

P2 = 0;
P2 = P2 | Hbyte;
P2 = P2 | 0x40; // E = 1
delay();
P2 = P2 & ~0x40; // E = 0
delay();
P2 = P2 | Lbyte;
P2 = P2 | 0x40;
delay();
P2 = P2 & ~0x40;
delay();
P2 = 0;
}
} End of Main

 

[Kurenai_ryu]

Lcd programming

schematic?

 

[millwood]

Lcd programming

I am guessing it is a hd44780 type display, configured in 4-bit mode, d4..7 on p2.0..3.

 

[FvM]

Lcd programming

The software init sequence ist not according to the manufacturers suggestions. The four first control writes (03,03,03,02) have to send
as single nibbles, not using LCD_Control(). Also the delay may be unsufficient. Read the datasheet thoroughly!

 

[millwood]

Lcd programming

The four first control writes (03,03,03,02) have to send as single nibbles, not using LCD_Control().

it can be sent using LCD_Control().

Also the delay may be unsufficient.

only if your chip is running much faster than 12Mhz.

Read the datasheet thoroughly!

good advice.

 

[FvM]

Re: Lcd programming

it can be sent using LCD_Control().

Yes, if you write:

LCD_Control(0x33); 
LCD_Control(0x32);

But the individual delay requirements are different, e.g. 4.1 ms after the first nibble. LCD_Control would be slowed down seriously if you do it like this.

only if your chip is running much faster than 12Mhz

A 8051 derivate clocked at 12 MHz can be either 1 or 12 MIPS fast. Can't be seen from the code.

 

[millwood]

Lcd programming

Yes, if you write:
Code:
LCD_Control(0x33);
LCD_Control(0x32);

no. it is fine as written by the original poster.

But the individual delay requirements are different, e.g. 4.1 ms after the first nibble. LCD_Control would be slowed down seriously if you do it like this.

in fact, that's incorrect: the datasheet just speicifies minimum timing. you can delay longer than the minimum.

A 8051 derivate clocked at 12 MHz can be either 1 or 12 MIPS fast. Can't be seen from the code.

what do you think a reasonable guess is?

Added after 2 minutes:

strategically, you identified exactly what went wrong with this code: the original poster's thorough lack of understanding of the device and its datasheet.

tactically, what you mentioned has zero impact on getting the code to work. There are a few glaring issues here that if mitigated can get the code to work quickly. and you identified none of them.

Added after 35 minutes:

well, I took the code, made three minor changes - none of them mentioned by FvM - and it worked!