IONI Pro feedback device

Can you please tell me if I can connect a single ended signal to IONI feedback pins? We have a weird feedback device with single ended SSI (essentially SPI). Or should I use RS-485 converter to make a true differential signal?

The reason I’m asking this is that I see some feedback pins for SSI (like GPI3, GPI2) can also accept single ended signals. But I’m not so sure about C- and C+ signals.

Also there is some conflicting specification on Wiki.
1.This schematic shows a 3.3V ESD protection on IO pins:

Although SSI communication is specified as RS422/RS485 which is ±5V or more!

  1. For SSI encoder it is specified that I should use pins 11, 12, 14, 15 on X2 connector. Here it shows they are all inputs(green):

But Clock pins should be output? How does that work?

Any ideas about the above question?


I’m sorry for the late reply.

The TVS diode in the schematics it 3.3 V version, which can be used with 5 V signals. The actual clamping voltage is higher enough that there is only marginally larger reverse current. I don’t remember if the actually assembled part is the 3.3 V or 5 V version, however it will work with 5 V encoder.

It’s possible to use single-ended signals.

Kind regards, Esa

Thank you for the reply.

I already tested it and single ended works. Clock is connected directly but data input is connected through similar schematic like here:

The resistor network(R1, R2) shown there will hold the inverting input at 2.5V and the other resistors will decrease the amplitude of the 5V signal.