This is more of a hardware question, but I’ll ask here just in case anyone is familiar. I am using the RFSoC4x2.
In the manual from Real Digital, it says “All 22 FPGA signals are routed as differential pairs.” When I investigate a particular PMOD bank, however, I’m not sure if this is true. For instance, take signals PMOD0_0 through PMOD0_7. In the board schematic, PMOD0_4 is routed to pin IO_T2U_N12_64 (AF15) on the FPGA. This pin seems to be single-ended. Further, PMOD0_2 maps to FPGA pin IO_L15P_T2L_N4_AD11P_64 (AJ16), but its opposite polarity partner, pin IO_L15N_T2L_N5_AD11N_64 (AJ15) is not connected to anything per the schematic.
Further, the pins that are paired don’t seem to follow a physical pattern on the header. PMOD0_3 and PMOD0_7 are a pair and are in a column (fourth column from right if looking at the header), while PMOD0_0 and PMOD0_5 are paired, but are rather in adjacent columns (they are in different rows though). Adjacent columns also for PMOD0_1 and PMOD0_6.
Below is a color-coded head-on view of the connector. Gray is not paired, neon blue is 3V3/GND, and same color means paired.
For my purposes, I’m actually going to just be using a single-ended signal, but I would really like to clarify what is going on with the hardware, because this is confusing me.
Any help appreciated!