mugur
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Hi guys. I am a beginner in c programming and I try to connect a 20x4 lcd to a pic16f877 through i2c module. The lcd is working if I connect it directly to pic. The i2c module is a cheap one from ebay, a mjkdz model like **broken link removed**. I have the code but my problem is that I can't make it work because I need to change the address. The initial address is 0xc6 and I need to change it to 0x20 or 0x27. The code is below:
I tryed to replace "SSPBUF = 0xc6;" with "SSPBUF = 0x20;" or "SSPBUF = 0x27;" but so far no luck
. Do I need to change something else in code or this should be enough?
I tryed to put 4.7k pull up resistors on SDA and SCL but is not working.
Please help me. Thank you.
Code:
#include <pic.h>
#include <stdio.h>
__CONFIG(0x3b32);
void clrscn(void); // prototypes
void cursor(char pos);
void print(char *p);
void setup(void);
char s[21]; // buffer used to hold text to print
void main(void)
{
setup(); // sets up the PIC16F877 I2C port
clrscn(); // clears the LCD03 disply
cursor(26); // sets cursor to center the text on 2nd row of LCD03
sprintf(s,"Hello World"); // Traditional welcome text, printed into our buffer
print(s); // send it to the LCD03
while(1); // just stops
}
void clrscn(void)
{
SEN = 1; // send start bit
while(SEN); // and wait for it to clear
SSPIF = 0;
SSPBUF = 0xc6; // LCD02 I2C address
while(!SSPIF); // wait for interrupt
SSPIF = 0; // then clear it.
SSPBUF = 0; // address of register to write to
while(!SSPIF); //
SSPIF = 0; //
SSPBUF = 12; // clear screen
while(!SSPIF); //
SSPIF = 0; //
SSPBUF = 4; // cursor off
while(!SSPIF); //
SSPIF = 0; //
PEN = 1; // send stop bit
while(PEN); //
}
void cursor(char pos)
{
SEN = 1; // send start bit
while(SEN); // and wait for it to clear
SSPIF = 0;
SSPBUF = 0xc6; // LCD02 I2C address
while(!SSPIF); // wait for interrupt
SSPIF = 0; // then clear it.
SSPBUF = 0; // address of register to write to
while(!SSPIF); //
SSPIF = 0; //
SSPBUF = 2; // set cursor
while(!SSPIF); //
SSPIF = 0; //
SSPBUF = pos; //
while(!SSPIF); //
SSPIF = 0; //
PEN = 1; // send stop bit
while(PEN); //
}
void print(char *p)
{
SEN = 1; // send start bit
while(SEN); // and wait for it to clear
SSPIF = 0;
SSPBUF = 0xc6; // LCD02 I2C address
while(!SSPIF); // wait for interrupt
SSPIF = 0; // then clear it.
SSPBUF = 0; // address of register to write to
while(!SSPIF); //
SSPIF = 0; //
while(*p) {
SSPBUF = *p++; // write the data
while(!SSPIF); //
SSPIF = 0; //
}
PEN = 1; // send stop bit
while(PEN); //
}
void setup(void)
{
unsigned long x;
TRISC = 0xff;
PORTC = 0xff;
SSPSTAT = 0x80;
SSPCON = 0x38;
SSPCON2 = 0x00;
SSPADD = 50; // SCL = 91khz with 20Mhz Osc
for(x=0; x<60000; x++); // wait for LCD03 to initialise
}I tryed to replace "SSPBUF = 0xc6;" with "SSPBUF = 0x20;" or "SSPBUF = 0x27;" but so far no luck
. Do I need to change something else in code or this should be enough?I tryed to put 4.7k pull up resistors on SDA and SCL but is not working.
Please help me. Thank you.
Last edited:
