2 Replies Latest reply on Jan 15, 2018 2:34 PM by alessandrocasella

    Why I2C Bus is busy with two devices?

    alessandrocasella

      Good evening,

       

      i'm trying to getting two MPU-9250 working via I2C with PSOC as Master.

      Connecting to the bus only one MPU-9250 everything works perfectly!

      Using two devices won't work, and the I2C_SendStart() says: I2C Bus Busy!

       

      Testing without any device connected the I2C_SendStart() function says at first attempt: I2C_NAK (it seems the right answer when no devices answers to the call of the PSOC), after from the second attempt I2C answers Bus Busy!  To free the bus i have to use the I2C_SendStop() function, but i using it yet... but doesn't free the bus.

       

      The MPU-9250 used is on a IMU breakout board by sparkfun: SparkFun IMU Breakout - MPU-9250 - SEN-13762 - SparkFun Electronics

       

      Thank you for support!

        • 1. Re: Why I2C Bus is busy with two devices?
          user_1377889

          Could it be that the pull up resistors from two devices are out of limit? Are you using a Cypress prototyping kit which also has gutpullups?

           

          Bob

          • 2. Re: Why I2C Bus is busy with two devices?
            alessandrocasella

            I don’t know for sure..

            Reading an NXT I2C datasheet i have read that for 400kbit speed i need a 1K pullup, according the IMU schema, it has an integrated 10K pullup.

            So is possibile that one IMU works and 2 doesn’t for this reason?

             

            Anyway i'm using a CY8KIT-059 (PSOC 5LP) Prototyping Kit

            Il giorno 15 gen 2018, alle ore 21:43, user_1377889 <community-manager@cypress.com> ha scritto:

             

             

             

            CYPRESS DEVELOPER COMMUNITY

             

            Why I2C Bus is busy with two devices?

            reply from user_1377889 in PSoC 5 - View the full discussion

             

            Could it be that the pull up resistors from two devices are out of limit? Are you using a Cypress prototyping kit which also has gutpullups?

             

             

             

            Bob

             

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