Using I2C on BBB

Hi IvanLai,

Are you working with device tree? If so then for every I2C device note you have a clock-frequency defined, as bellow:

        i2c1: i2c@4802a000 {
            pinctrl-names = "default";
            pinctrl-0 = <&i2c1_pins>;

            status = "okay";
            clock-frequency = <100000>;

You can change the setting of clock-frequency parameter here.

Best Regards,
Yordan

Hi:

            Unfortunately, i didn't use device tree, i only found some usage like this link(http://datko.net/2013/11/03/bbb_i2c), but i couldn't find any article mention that how to configure the clock of I2C.

Hi Ivan,

Are you using board file or dts file ?

If board file,

100 -> 100KHz of I2C1

 omap_register_i2c_bus(1, 100, am335x_i2c0_boardinfo, ARRAY_SIZE(am335x_i2c0_boardinfo));

Hi, I think i use board file, but i use the kernel from BBB official website provided. What header file i need to include to call this function?

Hi,

As Titus said, you should only call the register_i2c_bus function with appropriate clock rate. the header is already included <i2c.h>.

Best Regards,

Yordan

Hi :

                I include two file named <linux/i2c.h> and <linux/i2c-dev.h>, i can't find the definition of function that Titus said in these files?? did i include wrong header file??

Refer to the following files.

./arch/arm/plat-omap/i2c.c

./arch/arm/plat-omap/include/plat/i2c.h

Hi:

                  As you said, i include the header file, and now the compiler show me the error "u32 has not been declared"