[ARM] I2C interfacing using interrupts in LPC2138

[Ravindrakant Jha]

---

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
#include <LPC213X.H>
unsigned int I2Caddress;  //global variable for address
unsigned int I2Cdata;   //global variable for data
unsigned char *message;
void i2c_isr(void)__attribute__((interrupt("IRQ"))); //interrupt service routine
void i2c_transfer_byte(unsigned add,unsigned data); //function for transferring bytes
void i2c_receive_byte(void);     //function for receiving
void i2c_init()   //I2C initialization
{
  
  VICVectCntl1=0X00000029;// vectored control pin for I2C
  VICVectAddr1=(unsigned)i2c_isr;//passing IRQ address to the VIC slot
  VICIntEnable = 0x00000200; //enable interrupt
  PINSEL0|=0X50;//selecting  pin for I2C
  I2C0SCLL= 0X08;  //for a frequency of 57.6 KHz
  I2C0SCLH= 0X08;
}
void i2c_transfer_byte(unsigned add,unsigned data)
{   
    I2Caddress=add;
    I2Cdata=data;
    I2C0CONCLR=0X000000FF;//clear all I2c settings
    I2C0CONSET=0X00000040;//enable I2C 
    I2C0CONSET=0X00000020;//start condition
}
void i2c_isr(void)
{
    switch(I2C0STAT)
    {
      case(0X08): I2C0CONCLR=0X20; //clear start bit
                  I2C0DAT=I2Caddress;
                  break;
      case(0X18): I2C0DAT=I2Cdata; //send data 
                  break;
      case(0X20):I2C0DAT=I2Caddress;//resend slave address+W
                  break;
      case(0X28):I2C0CONSET=0X00000010;//stop condition
                  break;
    }
    I2C0CONCLR=0X08;//i2c interrupt clear bit
    VICVectAddr=0X00000000; //clear all interrupts
}
void i2c_receive_byte(void)
{
   switch(I2C0STAT)
   {
     case(0X40):I2C0CONSET=0x04; //SLAVE +READ+ack
                break;
     case(0X48):I2C0CONSET=0X20;//resend start condition
                break;
     case(0X50):*message=I2C0DAT; //receive data into message buffer
                I2C0CONSET=0X10;
                break;
     case(0X58):I2C0CONSET=0X20;//data received ,resend start condition
                break;
  }
  
}
int main()
{
  int addr=0X00;
  i2c_init();
  i2c_transfer_byte(addr,'R');
  i2c_receive_byte();
  i2c_isr();
}

---

by executing above code the interrupt enable bit is not getting set though i declared in the i2c_init function as well on the keil i2c module data is shown only received with the value shown 02!

 

[FvM]

It's mysterious what you want to achieve. An interrupt service routine would be never called from main.