Sorry you're running into this. It could certainly be clearer in our documentation for the filter wizard evaluation boards.
The EVAL-FW-MOTHER motherboard is a four layer board. Layer 2 is "GND" and layer 3 is "REF". "REF" on the motherboard is connected to the daughterboards through the two middle pins of the 6 pin motherboard-daughterboard connector. Since this connection is to the internal plane, there aren't any traces to see. The daughterboards do not directly connect to "GND" on the motherboard.
By default this REF plane on the motherboard isn't connected to anything. For things to work, you have to connect it to something using one of the "JP" jumpers. The motherboard supports three different ways of setting the REF potential:
- Dual supply case: (i.e. what you have) Put a 0 ohm jumper across JP2. This will connect REF to GND.
- Single supply case: Put a 0 ohm jumper across JP1. This will connect REF to the single supply reference voltage generator.
- ADC board case: The motherboard also can accept a reference voltage from some of our ADC evaluation boards through the ADC power connector in the upper right hand corner of the board. If you were to use this method, you would put a 0 ohm jumper across JP3.
I've attached the motherboard schematic (should also be in the design packet you downloaded), where you can see how REF gets set. (See middle of the page).
Matt