4 Replies Latest reply on Mar 6, 2011 9:32 PM by

    I2C vs. SMBus in ICH8

    zvivered

      Hello,

       

      According to the datasheet of ICH8 (313056.pdf, page 225):

       

      "The ICH8 is also capable of operating in a mode in which it can communicate with I2C compatible device"

       

      I have few I2C slave devices connected to the I2C interface (and not to SMBus interface).

       

      But there is no info in the datasheet how to read/write bytes using this interface.

       

      The SMBus interface is well documented.

       

      Can you help ?

       

      Thanks.

       

        • 1. Re: I2C vs. SMBus in ICH8
          Doc_SilverCreek

          I2C & SMBus are 2 closley related serial electrical specifications.

           

          Check the Appendix B of the SMBus specification for a listing of the differences. http://smbus.org/specs/smbus110.pdf

           

           

          • 2. Re: I2C vs. SMBus in ICH8

            I'm aware that SMBus and I2C are 2 closely related.

            ICH8 has 2 interfaces: I2C and SMBus.

            How can I use I2C instead of SMBus ?

             

            Thanks.

            • 3. Re: I2C vs. SMBus in ICH8
              Doc_SilverCreek

              I am afraid I don't know enough about what you are trying to do to give you a good answer.

              I could go down any of the paths below. (although I try to stay away from software.... Gives me a headache)

               

              Are you adding I2C slave device to a existing mother board and asking how to wire it?

              Are you adding I2C slave device to a existing mother board and asking how communicate with it?

                   This would be dependant on the the mother board and smbus interface and the device addressing.

              Are you adding I2C master device to a existing mother board and and asking how the device can control the ICH8?

              Are you designing a mother board using the ICH8 and want to enable in your BIOS communicate in I2C mode?

              Are you asking how to set the registers bits in 16.1.15 HOSTC—Host Configuration Register (SMBUS—D31:F3) Pg 630

                   The board BIOS/BMC configures these registers and many boards do not expect any changes of other bus masters so when changing them you may generate conflicts.

              • 4. Re: I2C vs. SMBus in ICH8

                Hello,

                 

                According to the vendor of my board there is no I2C interface. Only SMBus.

                 

                So the issue is solved.

                 

                Thank you for your help.