ARM7 to ARM7 (LPC2148) communication using I2C

     Board to board communication using I2C protocol, is simple once you’ve done any other program using this protocol with arm7. Since I have interfaced arm7 with eeprom. The same code used to send data to the eeprom is been used,except for the change in slave address,in this case it’s (0x00);

SEND

Master transmit mode

#include<lpc214x.h>
#include<stdio.h>
#include”appdef.h”
#include”armlcd.h”
#define led_port BIT0+BIT1+BIT8+BIT9+BIT25+BIT15+BIT12+BIT28
int c=1;
int r=0;
static int i=0;
unsigned char buf[12]=”YES YAMAHA”;
__irq void led(void)
{
     IOSET0=led_port;
     switch(I2C0STAT)
     {
         case 0x08 : lcd(‘s’); //start
                             I2C0CONCLR=BIT3+BIT5;

                             I2C0DAT=0x00;  //slave address of the other board

                             break;
          case 0x18 : lcd(‘a’);
                             I2C0CONCLR=BIT3;
                             break;
         case 0x28 : lcd(‘k’);
                            I2C0CONCLR=BIT3;
                            switch(c)
                            {
                               case 1 : I2C0DAT=buf[i];
                                             i++;
                                            if(i==10)
                                            {
                                                c++;
                                             }
                                             break;
                              case 2: I2C0CONSET=BIT4;
                                           lcd(‘p’);
                                           break;
                            }
                              break;
       case 0x30 : lcd(‘n’);
                          I2C0CONCLR=BIT3+BIT5;
                          break;
       default:      lcd(‘f’);
                         break;
}

VICVectAddr=0x00;
}

int main()
{

rs_clr();
en_clr();
lcd_init();
rs_set();
en_clr();
lcd(‘i’);
PINSEL0=BIT4+BIT6;

VICVectCntl0=0x29;
VICVectAddr0=(unsigned) led;
VICIntEnable=BIT9;

I2C0CONSET=BIT6;
I2C0CONCLR=BIT3+BIT2+BIT4;
I2C0SCLH=0x4B;
I2C0SCLL=0x4B;

I2C0CONSET|=BIT5;
while(1);

}
void lcd_init()
{
unsigned int i;
PINSEL0 = 0x00000000;

lcd_dir_write(); // output port
for (i=0;i<1000;i++);
lcd(0x33);
lcd(0x32);
lcd(0x28);
lcd(0x0e);
lcd(0x01);
lcd(0x06);
lcd(0x80);

for (i=0;i<1000000;i++);
}

void lcd(unsigned char val)
{
lcd1(val>>4);
lcd1(val);
}

void lcd1(unsigned char c)
{
unsigned int i;
IOCLR0 = 0x00f00000;
IOSET0 = (c<<20); // d4 connected to 20th port pin
en_set();
for (i=0;i<1000000;i++);
en_clr();
}

RECEIVE

Slight changes at the code at the slave side.You have to choose the arm controller to be in slave mode.

Slave receiver mode.

I2C0ADR=0X01; // general call address.Only when you set bit0 of this register can the master board send address as 0x00 to the slave board.

Enable bit & AA bit of the I2CCONSET register has to set to 1 during initialization. 

Remember no start bit required.

status codes are 0x70,0x90. go through the user manual

#include<lpc214x.h>
#include<stdio.h>
#include”appdef.h”
#include”armlcd.h”
#define led_port BIT0+BIT1+BIT8+BIT9+BIT25+BIT15+BIT12+BIT28
int c=0;
int r=0,dw=1,ss=0,rs=0,j;
char ch;
__irq void led(void)
{
        switch(I2C0STAT)
       {
           case 0x70 : lcd(‘g’);  
                              I2C0CONSET|=BIT2;  //AA bit set
                              I2C0CONCLR=BIT3;
                              break;
           case 0x90 :ch=I2C0DAT;  //data received and stored safely
                             I2C0CONCLR=BIT3;
                             lcd(ch);
                             break;
           case 0xa0 :lcd(‘p’);
                             I2C0CONCLR=BIT3;
                             break;
           default:lcd(‘f’);
                       I2C0CONCLR=BIT3;
                       break;
}

VICVectAddr=0x00;
}

int main()
{

rs_clr();
en_clr();
lcd_init();
rs_set();
en_clr();
PINSEL0=BIT4+BIT6;
VICVectCntl0=0x29;
VICVectAddr0=(unsigned) led;
VICIntEnable=BIT9;

I2C0ADR=0X01;  // general call addr
I2C0CONSET=BIT6+BIT2; // SLAVE MODE
I2C0CONCLR=BIT3;
I2C0SCLH=0x4B;
I2C0SCLL=0x4B;

lcd(‘v’);
while(1);
}
void lcd_init()
{
unsigned int i;
PINSEL0 = 0x00000000;

lcd_dir_write(); // output port
for (i=0;i<1000;i++);
lcd(0x33);
lcd(0x32);
lcd(0x28);
lcd(0x0e);
lcd(0x01);
lcd(0x06);
lcd(0x80);

for (i=0;i<1000000;i++);
}

void lcd(unsigned char val)
{
lcd1(val>>4);
lcd1(val);
}

void lcd1(unsigned char c)
{
unsigned int i;
IOCLR0 = 0x00f00000;
IOSET0 = (c<<20); // d4 connected to 20th port pin
en_set();
for (i=0;i<1000000;i++);
en_clr();
}

Interfacing external memory with LPC2148 using I2C Protocol (PART 2)

Dummy write operation

So once your done with writing data into the EEPROM,you would want to read from the location where you have written into.

The diagram above clearly shows the steps how it needs to be done. 

CODE:

#include<lpc214x.h> // standard header file
#include”appdef.h” // defining bits,example:#define BIT0 0x01<<0
#include”armlcd.h” // initialisations for lcd
#define led_port BIT0+BIT1+BIT8+BIT9+BIT25+BIT15+BIT12+BIT28
int c=0;
int r=0,dw=1,ss=0,rs=0,j;
char ch;
__irq void led(void)
{
switch(I2C0STAT)
{
case 0x08 : //lcd(‘s’); // 1.start
                  I2C0CONCLR=BIT3; 
                  I2C0DAT=0xa0; // dummy write
                  break;
case 0x10 :// lcd(‘b’); // 4. repeated start condition status
                   I2C0CONCLR=BIT3+BIT5;
                  I2C0DAT=0xa1; // read
                  break;
case 0x18 : //lcd(‘a’); // 2. write  ack
                   I2C0CONCLR=BIT3+BIT5;
                   I2C0DAT=0x00; // memory address
                   break;
case 0x28 : //lcd(‘k’); // 3. ack
                   I2C0CONCLR=BIT3;
                   I2C0CONSET|=BIT5; // repeated start bit
                   break;
case 0x40 : //lcd(‘r’);  // 5.read ack
                   I2C0CONCLR=BIT3;
                   I2C0CONSET=BIT2; // aa flag
                   break;
case 0x48 : lcd(‘l’);
                   I2C0CONCLR=BIT3;
                   break;
case 0x50 : I2C0CONCLR=BIT3; // 6.start receiving data
                   ch=I2C0DAT;
                   lcd(ch);
                  if(dw==9)
                  {
                       I2C0CONCLR=BIT2;  // sending a no ack after reading 10 bytes
                  }
                  dw++;
                  break;
case 0x58 ://lcd(‘n’);   // 7.stop bit
                   I2C0CONCLR=BIT3;
                   I2C0CONSET=BIT4;
                   break;
default:lcd(‘f’);
             I2C0CONCLR=BIT3;
              break;
}

VICVectAddr=0x00;
}

int main()
{

rs_clr();
en_clr();
lcd_init();
rs_set();
en_clr();
//lcd(‘i’);
PINSEL0=BIT4+BIT6;
VICVectCntl0=0x29;
VICVectAddr0=(unsigned) led;
VICIntEnable=BIT9;

I2C0CONSET=BIT6;
I2C0CONCLR=BIT3;
I2C0SCLH=0x4B;
I2C0SCLL=0x4B;

I2C0CONSET|=BIT5; //start
while(1);
}
void lcd_init()
{
unsigned int i;
PINSEL0 = 0x00000000;

lcd_dir_write(); // output port
for (i=0;i<1000;i++);
lcd(0x33);
lcd(0x32);
lcd(0x28);
lcd(0x0e);
lcd(0x01);
lcd(0x06);
lcd(0x80);

for (i=0;i<1000000;i++);
}

void lcd(unsigned char val)
{
lcd1(val>>4);
lcd1(val);
}

void lcd1(unsigned char c)
{
unsigned int i;
IOCLR0 = 0x00f00000;
IOSET0 = (c<<20); // d4 connected to 20th port pin
en_set();
for (i=0;i<1000000;i++);
en_clr();

}