Ben Williams

Sharing Dif I2C Lines on the PCA9615 from I2C to GPIO/Analogue

Discussion created by Ben Williams on Jul 28, 2020
Latest reply on Jul 29, 2020 by G.w. Sun



I'm certainly developing an adaptable interface that can allow me to connect various devices into my system. At the moment  the interface types that can connect are:

  1. I2C Controller
  2. GPIO/Analogue: Adaptive button, joysticks, etc.

Device connection wise, I'm designing it to use two 3.5mm 4 pole audio jacks as a connection to the interfaces. This will give me two channels for GPIO/Analogue inputs. 


When connecting an I2C interface both 3.5mm jacks will be used.


I'm planning in using the PCA9615 to provide dif I2C to the I2C interface device which could be 2M away. To achieve this Dif SDA and Dif SCL will be split across the two 3.5mm jacks.


Just so the Dif I2C lines don't interrupt with the possible GPIO/Analogue devices I was thinking of using a (2:1) x 4 Analogue Switch to disconnect the Dif I2C lines. I believe the ADG888 might be suitable. 


The system Micro-controller with be set-up to know which device is being connected from startup;


Normal Operation: (GPIO/Analogue Default)

  1. Power to PCA9615 Disabled.
  2. Enabled kept HIGH
  3. Dif I2C lines Disconnected from the COM switch point.
  4. GPIO/Analogue Lines connected to COM switch point

I2C Operations:

  1. Dif I2C lines Connected from the COM switch point.
  2. GPIO/Analogue Lines connected to COM switch point
  3. Power to PCA9615 Enabled.
  4. Enabled Pulled LOW to start the device.


Are there any particular issues with this?  


Below is a very basic connection diagram:



Thank you for your time