8 Replies Latest reply on Aug 15, 2016 7:49 AM by user_1269049

    PSOC 4200 I2C Raspberry Pi 2 doesn't work for 5V

    r.s.jahn_1564316

      Hello,

         

      I try to connect an PSOC 4200 ( CY8CKIT-049-42XX) as slave via I2C to an Raspberry Pi 2 as master.

         

      With 3.3V on 4200 from Raspberry, all works fine, with 5V over USB on kit nothing happens on SDA and SCL.

         

      SDA is stays at 3.3V, but SCL is about 5V ? No signal to see on scope or LA.

         

      I thought I2C should work with both voltages on one line.

         

       

         

      Where do 5V come from ? 4200 I2C lines should open drain high side or ?

         

      Then 5V can only come over high impedance, whereas Raspberry has 1.8K to 3.3V,

         

      which should result in about 3.3V ?

         

      What is the high threshold of both lines in this mode ? I find different CMOS and LVTTL in datasheet.