I2C test application from userspace

[srinivasanshanm]

Dear All,

I'm trying to write the eeprom userspace test application,

when I run the below test app, I see the below messages

BusyBox v1.15.0 () built-in shell (ash)

Enter 'help' for a list of built-in commands.

root@freescale ~$ MY_TEST_APPLICATION_EEPROM

SUCCESS: open(3) passed

ERROR: ioctl(fd, I2C_SLAVE, 0x50) failed

root@freescale ~$

I even tried changing it to   "status = ioctl(fd, I2C_SLAVE_FORCE, i2c_addr);"  , but still the same issue, could you please let me know how to get rid of this issue, as am trying this from since 2 days, not able to succeed further

Any help would be greatly appreciated

Thanks in advance,

#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/ioctl.h>

#include <fcntl.h>

#include <linux/fs.h>

#include <errno.h>

#include <string.h>

#include <linux/i2c-dev.h>

#include <linux/i2c.h>

    /* chmod 666 /dev/i2c-0 */

int main(void)

{

       // Data to be written to eeprom

unsigned char wbuf[17] =  {   0x00, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F };                

unsigned char rbuf[16];

int i2c_addr = 0xa0;

int status;

unsigned short int i;

// OPENING I2C DEVICE

int fd = open("/dev/i2c-0", O_RDWR);

if (fd < 0) {

printf("ERROR: open(%d) failed\n", fd);

return -1;

}

  printf("\nSUCCESS: open(%d) passed\n", fd);

// SETTING EEPROM ADDR

    status = ioctl(fd, I2C_SLAVE, i2c_addr>>1);

    if (status < 0)

    {

printf("ERROR: ioctl(fd, I2C_SLAVE, 0x%02X) failed\n", i2c_addr);

close(fd);

return -1;

        }

    printf("\nSUCCESS: ioctl(fd, I2C_SLAVE, 0x%02X>>1) passed\n", i2c_addr);

// WRITING TO EEPROM

printf ("\nPerforming EEPROM Write operation\n");

write(fd,wbuf,16);

sleep(10); //till eeprom completes writes

if (write(fd,wbuf,16) != 16) {

printf("ERROR: write() failed\n");

close(fd);

return -1;

}

printf("\nSUCCESS: Data written to the EEPROM\n");

// READING FROM EEPROM

printf ("\nPerforming EEPROM Read operation\n");

wbuf[0]=0;

if(write(fd,wbuf,1)!=1){

printf("ERROR: buffer pointer initialization of read() failed\n");

}

  if (read(fd,rbuf,16) != 16) {

printf("ERROR: read() failed\n");

close(fd);

return -1;

}

for(i = 0; i< 16; i++)

printf("ReadBuffer[%d] %d \r\n", i, rbuf[i]);

printf("\nSUCCESS: Data READ from the EEPROM\n");

printf("\neerprom test successfull \n");

close(fd);

}

[YixingKong]

Srinivasan

Had your issue got resolved? If yes, we are going to close the discussion in 3 days. If you still need help please feel

free to contact Freescale.

Thanks,
Yixing

[srinivasanshanm]

Please close this issue it is resolved, thanks a lot for your support

[raymondwang · Accepted solution]

You can refer to http://www.lm-sensors.org/browser/i2c-tools/trunk/eepromer?rev=5202

There are some examples of i2c utilities to access EEPROM (also including 24Cxx serial eeprom).

[srinivasanshanm]

Could anybody please do the needful in addressing the above thread, as early as possible,

Any help would be greatly appreciated,

Many Many thanks in advance again...

[Raybiztech]

Hi Srinivasan,

     There can be 3 different possibilities,

1) Each registered i2c adapter gets a number starting from 0 ,check eeprom is connected to which adaptor.  

     see /sys/class/i2c-dev/ to see what number corresponds to which adapter.

2) verify eeprom address in datasheet.

3) I think Right shift operation is not necessary as generally driver is take care of sending 7 bit device address in upper bits of byte.

If you share eeprom datasheet as well as board specification it will be better.

Regards,

sasidhar

[srinivasanshanm]

Hi sasidhar

Thanks a lot for your response,

Am using eeprom 24c08, whose slave address is 0x50

Please find the attached datasheet, evn I tried giving seven bit address this didnt work for me

Thanks in advance

[Raybiztech]

Hi Srinivasan,

      If you look into data sheet the first 4 bits of device address always be 1010 ie. 0xa while last 4 bits can be changed based on "Table 3. Device Select Code" on page no 3 of datasheet. check for chip enable pin(3) is connected to vcc or gnd ie 1 or 0. if that pin is connected to 1 then b3 bit of address should be 1 & if pin is connected to 0 then b3 bit of address should be 0.otherwise device wont response.

if chip enable pin is 1 then device address is 10101XXX

if chip enable pin is 0 then device address is 10100XXX.

Please read "write operation" on page no 7 of data sheet carefully.

also refer following link

https://www.kernel.org/doc/Documentation/i2c/dev-interface

regards,

Sasidhar