topic i2c baudrate in i.MX Processors

i2c baudrate

ashokp — Tue, 16 Sep 2014 15:56:33 GMT

Hi All,

I am working on IMX6 custom board. I ported Android kitkat BSP from freescale for my custom board. In my I2C3 bus different speed slave devices are connected.

Please let me know how do i change the I2C bus speed (Baudrate ). Is it possible to have different speed for each slave devices ?

Thanks,

P.Ashok

Re: i2c baudrate

PeterChan — Wed, 17 Sep 2014 07:09:41 GMT

The I2C bitrate is fixed for each I2C bus. The bitrate can be configured at the struct imxi2c_platform_data in your kernel board-mx6X_XXXX.c.

The I2C slave can slow down the actual bitrate using clock stretching (see I2C Controller in reference manual for the detail).

Re: i2c baudrate

igorpadykov — Wed, 17 Sep 2014 09:51:11 GMT

Hi Ashok

please look at

Optional properties:

- clock-frequency : Constains desired I2C/HS-I2C bus clock frequency in Hz.

The absence of the propoerty indicates the default frequency 100 kHz.

https://github.com/alphalem/linux-yocto-3.10/blob/master/Documentation/devicetree/bindings/i2c/i2c-imx.txt

Best regards

igor

Re: i2c baudrate

ashokp — Wed, 17 Sep 2014 12:23:08 GMT

Hi ,

I am using Kernel version 3.0.35. This is the kernel from IMX6 freescale Android kitkat version.

The i2cdect command from serial console is not listing any i2c devices in I2C bus 3. The other i2c buses 1 and 2 are working fine.

I probed the SCL ans SDA lines of I2C3 i didn't see any signals when i access the i2C3 bus using i2c tools

Is I2C3 is tested in the kernel version 3.0.35 from (IMX6_KK442)?

I want to cross check the I2C physical address. Please let me know which file i can cross check for 3.0.35 kernel version. This kernel version don't have support for device tree.

Also i want to take the I2C3 register dumps. Please let me know if any idea on this

Thanks,

P.Ashok

Re: i2c baudrate

igorpadykov — Wed, 17 Sep 2014 13:11:08 GMT

Hi Ashok

for I2C bus 3 and i2cdect problems

please create new thread.

Best regards

igor

Re: i2c baudrate

kennywang — Sat, 31 Jan 2015 07:28:22 GMT

Hello,

Have the I2C different speed issue found solve, I meet the same problem, could you share me the solution? Thank you