SCPA063 March   2023 PCA9306

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2General Checks for Dealing With NACKs
    1. 2.1 NACKs
    2. 2.2 Check the Schematic
    3. 2.3 Double Check SDA and SCL Between the Controller and Target
    4. 2.4 RESET Properly Biased
    5. 2.5 Device is Soldered Properly
  5. 3Scopeshots
    1. 3.1 Why use Oscilloscopes for Debugging?
    2. 3.2 Setting up the Oscilloscope
    3. 3.3 Verify the I2C Address When a NACK is Received
    4. 3.4 Validate Start and Stop Conditions
    5. 3.5 Check the Byte Format
    6. 3.6 Are Rise Times Within I2C Standard?
    7. 3.7 Are the Sent Command Bytes Valid?
  6. 4I2C Switches
    1. 4.1 Stop Conditions for TI I2C Switches
  7. 5I2C Buffers
    1. 5.1 VoL versus ViLc of the Buffer
    2. 5.2 VoL of the Buffer Exceeds the ViL of the I2C Target
    3. 5.3 Static Offset of Buffers Cannot Connect to Other Static Offsets
  8. 6Checklists
  9. 7Conclusion

5.2 VoL of the Buffer Exceeds the ViL of the I2C Target

VoL on the buffer side cannot exceed the ViL level of the connected devices. If VoL exceeds ViL, the device is unable to recognize a logic low when the I2C bus is pulled low. To prevent this from happening, always verify that VoL is less than ViL by checking the data sheets of the buffers and connected devices.