2 Replies Latest reply on Sep 24, 2014 6:57 AM by user_14586677

    I2CHW Voltage

    cheng.chen

       Hello,

         

      Can anyone tell me how to set I2CHW UM operating voltage to 3.3V or 5V? I set my PSoC1 system power setting to 5V, but the i2cHW still operates at 3.3V. I didn't find anywhere to change the i2c voltage and hope anyone can help out.

         

      Thanks!

         

      CC

        • 1. Re: I2CHW Voltage
          ki.leung

          Do you have pull up resistor to VCC on the 2 I2C pins? what is the voltage on the other side of the resistor?

          • 2. Re: I2CHW Voltage
            user_14586677

            The logic high level for I2C is set by the Vdd supply for

               

            the pullup R's. If you are using internal pullups they get

               

            powered by whatever the PSOC Vdd is. If you use external

               

            pullups and terminate them to 3.3V, noise margin in.

               

            this situation significantly reduced. The min "1" level is .7 x Vdd