This Library can be used to communicate with the I2C protocol for the ADXL312 Digital Accelerometer in Embedded Linux Systems.
You can find detailed definitions of ADXL312 in the adxl312_io.h library.
i2c_init function takes 2 parameters. They are \*i2cdevice and addr. This function open device and talk with i2c slave. If connection has any error return -1. If connection is Ok than return opened file data.
int i2c_init(char *i2cdevice,int addr){
int file;
if( ( file = open(i2cdevice,O_RDWR)) < 0 ){
perror("Failed to open the i2c bus\n");
return -1;
}
if( ioctl(file,I2C_SLAVE,addr) < 0 ) {
printf("Failed to talk i2c\n");
return -1;
}
return file;
}i2c_writeByte function takes 3 parameters. They are file,addr and value. file is opened device and addr is the address to be written and value is the value to send. This function returns 1 if write correctly else return -1.
int i2c_writeByte(int file,int addr,int value){
char buf[10] = {0};
buf[0] = addr;
buf[1] = value;
if(write(file,buf,2) != 2){
printf("Error setting i2c device\n");
return -1;
}
return 1;
}i2c_writeBytes function takes 4 parameters. They are file,addr, value[] and nbytes. file is opened device and addr is the address to be written, value[] is the array values to send and nbytes shows how many bytes are written. This function returns 1 if write correctly else return -1.
int i2c_writeBytes(int file,int addr,char value[10],int nbytes){
int i;
unsigned char buf[10] = {0};
buf[0] = addr ;
for(i=0;i<nbytes;i++)
buf[1+i] = value[i];
if(write(file,buf,nbytes) != nbytes){
printf("Error writing bytes to i2c device\n");
return -1;
}
return 1;
}i2c_readByte function takes 2 parameters and its returning type is a char. file is opened device and addr is a address to be read. This function returns the byte value read from the address if read is successful, otherwise returns -1.
char i2c_readByte(int file,int addr){
char buf = addr;
if(write(file,&buf,1) != 1 ){
printf("Error reading byte from i2c device\n");
return -1;
}
buf = '\0';
if(read(file,&buf,1)!=1){
printf("Error reading byte from i2c device\n");
return -1;
}
return buf;
}This function takes 4 parameters. It reads more than one address from device. This function freturns 16 bit byte value read from the address if read is successful, otherwise return -1.
int i2c_readByte(int file,int addr1,int addr2){
char buf1,buf2;
int fl = 0x0000FFFF;
if(write(file,&addr1,1) != 1 ){
printf("Error reading byte from i2c device\n");
return -1;
}
if(read(file,&buf1,1)!=1){
printf("Error reading byte from i2c device\n");
return -1;
}
if(write(file,&addr2,1) != 1 ){
printf("Error reading byte from i2c device\n");
return -1;
}
if(read(file,&buf2,1)!=1){
printf("Error reading byte from i2c device\n");
return -1;
}
printf("::: 0x%02x ::: 0x%02x \n",buf1,buf2);
int bf = ((int)buf1 << 8) | buf2;
return (fl&bf);
}*i2c_readBytes function takes 3 parameters and its returning type is a char*. file is opened device, addr is a address to be read and nbytesshows how many bytes are read. This function returns the byte array value read from the address if read is successful, otherwise returns NULL.
char *i2c_readBytes(int file,int addr,int nbytes){
char *bufx;
if( ( bufx = (char*)calloc(nbytes,sizeof(char)) ) == NULL ){
printf("Error allocating buffer...\n");
return NULL;
}
char buf = addr;
if(write(file,&buf,1) != 1 ){
printf("Error reading bytes from i2c device\n");
return NULL;
}
if(read(file,bufx,nbytes) != nbytes){
printf("Error reading byte from i2c device\n");
return NULL;
}
return bufx;
}Close opened file function.
int i2c_close(int file){
if(close(file)!=0){
printf("Error while closing file...\n");
return -1;
}
return 1;
}
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