topic Re: imx23 and i2c general issue in i.MX Processors

imx23 and i2c general issue

Fabio1z — Wed, 16 Nov 2011 15:42:53 GMT

Hallo,

maybe this question is very basic, but unfortunately I was not able to find a solution, neither in this forum, nor elsewhere.

My goal is: to let the I2C working on the EVK and on our custom board with iMX23.

I have configured ltib in such a way to support I2C as master.

After correctly booting from SD:

1) modprobe i2c-dev:

>>>>> i2c /dev entries driver

2) echo "a" > /dev/i2c-0

and all that i get is that the SCK line toggles correctly while the SDA still remain pulled up to VDDIO.

The same behaviour appear also if i run this simple program:

int fds;

char buf[2];

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

ioctl(fds,I2C_SLAVE,0x29);

buf[0] = 0xAA; buf[1] = 0xBB;

write(fds,buf,2);

Could anyone can help me to understand what I miss to do or to find an error?

Thanks in advance,

Fabio

Re: imx23 and i2c general issue

hake — Sat, 19 Nov 2011 05:31:05 GMT

maybe you should change the i2c from DMA mode to poll mode

Re: imx23 and i2c general issue

Balaji_ng — Wed, 23 Nov 2011 05:52:30 GMT

Hi Fabio,

Check if your pullup resistor values are correct. You may also try increasing the drive strength of the I2C Lines.

Regards,

Balaji

Re: imx23 and i2c general issue

Fabio1z — Wed, 23 Nov 2011 18:17:19 GMT

Dear,

thanks for your answers.

The electrical connection were ok (pull-up added, and pins configured correctly). The drive strength 4mA was enough for 4.7k pullup. Anyway I tried also to increase it.

I've definetively checked on the EVK board, using the pin as GPIO, and with the memtool (in the imx test), drive them directy. Unfortunatly the SDA pin was broken. On another board (and on my custom board), everything were ok.

Thanks again for your kind answers.

Fabio