[PIC] I2C data transfer between separate ground planes.

[fernando306]

Hi There, how are you?

I am currently working in an equipment that needs to have two separate grounds. The problem is that the microcontroller (PIC24) needs to be at GND1 and the DSPs at GND2 and they must communicate via I2C. I figured I could use photocouplers, so I tried with PC817 photocouplers but they're not fast enough. The I2C runs at 400Khz. Would you have any ideas to establish this communication between isolated ground planes? Any help will be very welcome!

Thank you very much!

Best wishes,

Fernando

 

[paulfjujo]

Hello,

Use better high speed photocoupler cut_off frequency 80KHz for the ¨PC817
see fig 11 on datasheet


maybe to much performant !

Show your hardware drawing .. and the load on output phtocoupler

 

[FvM]

A google search for "I2C isolator" will show you some of-the-shelf products for your application.

Do you understand that (apart from speed issues) simple digital opto couplers aren't suitable without additional I2C bus translator ICs to isolate the bidirectional bus lines?