How to read i2c with out i2cget command? - embedded-linux

Question

I am currently using Kontron smarc-samx6i board and I am running this board with Yocto kernel. Here the kernel is not supporting the command i2cget to check i2c data to read from sensor. So, is there any other possible ways to read i2c data from the sensors?

Answer 1

You can add "i2c-tools" to your image:
IMAGE_INSTALL_append = " i2c-tools"
They include i2cget.c.
The recipe can be found in: /meta/recipes-devtools/i2c-tools/

Answer 2

You might also want to look into writing your own application using the i2c dev interface. See the kernel documentation on i2c.

Answer 3

read:
#include <stdio.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
#include <errno.h>
#define I2C_ADDR 0x20
int main (void) {
char buffer[1];
int fd;
fd = open("/dev/i2c-0", O_RDWR);
if (fd < 0) {
printf("Error opening file: %s\n", strerror(errno));
return 1;
}
if (ioctl(fd, I2C_SLAVE, I2C_ADDR) < 0) {
printf("ioctl error: %s\n", strerror(errno));
return 1;
}
buffer[0]=0xFF;
write(fd, buffer, 1);
read(fd, buffer, 1);
printf("0x%02X\n", buffer[0]);
return 0;
}
write:
#include <stdio.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
#include <errno.h>
#define I2C_ADDR 0x20
int main (void) {
int value;
int fd;
fd = open("/dev/i2c-0", O_RDWR);
if (fd < 0) {
printf("Error opening file: %s\n", strerror(errno));
return 1;
}
if (ioctl(fd, I2C_SLAVE, I2C_ADDR) < 0) {
printf("ioctl error: %s\n", strerror(errno));
return 1;
}
for (value=0; value<=255; value++) {
if (write(fd, &value, 1) != 1) {
printf("Error writing file: %s\n", strerror(errno));
}
usleep(100000);
}
return 0;
}