jlab_xilinx

For future readers, I think the reason why Digilent does not provide this circuit is because they don't want you to include the FT2232HQ in your design, thinking that this will somehow let you program your S7 over USB. The FT2232HQ that the boards come with is loaded with a secret sauce EEPROM code which is not public. So just because you have this FT2232HQ chip on your board, doesn't mean you will be able to use it if you are trying to replicate this interface. But if you are stubborn, and want to go this route anyway, I think this design describes how to interface your S7 with FTE2232 chip: https://www.xilinx.com/products/boards-and-kits/sp701.html Best, -James

Hello, I am looking at the Cmod S7 evaluation board and I am interested in how to connect the FT2232HQ and the Spartan-7 together. When I look at the schematic, this information is not available (see sheet 5, 'intentionally left blank'). Does anyone have this missing page? https://s3-us-west-2.amazonaws.com/digilent/resources/programmable-logic/cmod-s7/Cmod+S7_sch-public.pdf Best Regards, James

Thank you all for your feedback. I assumed Digilent had good quality control for their products, it must have been damaged at some point in our Lab. We will just need to find a way to work around this one pin. Thanks, James

Hi Richm, Thank you for your response. What if I configure that specific FPGA pin to be HI-Z output, what is the maximum current that I can supply to the path between that pin and ground in order to 'burn' off the solder bridge? My plan is to make a dummy .bit file which sets all of the pins to hi Z output (3.3v). Then, I would inject a 3.3v DC voltage at a low current between the board's ground and the FMC pin in question. My thought it to apply only what the pin is rated for (10 mA, 100 mA maybe?) when configured in HI Z. I would very much like to not destroy this board. Thanks again, James

Thank you for your feedback. If I probe FMC pin H8 (which is FPGA pin L18) I see a near short to ground (several ohms). My best guess is that one of the ground pins on the FMC has a little solder bridge to FMC pin H8. I am doing this measurements with the FPGA off and unpowered (and not plugged in). Maybe this is a little risky, but what if I apply a 3v high amperage voltage to this pin and the nearest FMC ground pin. The goal would be to burn the solder bridge away. What do you think? -James

Also, underneath the Digilent board I see the rev number. It is REV A and I have been using schematic with REV A.0 (which I assume is the same?)

Hi Zygot, thank you for your reply. Where should I look on my board to make sure the schematic matches the actual board rev? Thank you for your response. The pin in question is FPGA pin L18 which goes to FMC_LA02_n. I am using this L18 pin as a reset pin on a mezzanine board that connects to the FMC. Probing it with an oscilloscope, I don't see it resetting. I have other similar pins which I do see resetting but not L18. I also have tied this pin to a constant HI (and some other pins just as a sanity check). I see the other pins as HI's but not L18. I also tried to use a weak pull up to force the pin HI (while driving L18 pin HI, as a constant), but the FPGA appears to be pulling the pin low. I also tried ohming out this connection to ground and I don't see any shorts to ground for pin L18. Do you have any additional debug suggestions? Thank you, James

Hello, I am working with the FMC on the digilent video board. Most of the pins appear to be mapped correctly but I am reasonably confident that some of the FMC pins do not match the schematic. Has anyone else had issues with the FMC pinout? Is there a way to get a hold of the actual board files to verify the FPGA to FMC trace routing agree with the published schematic? Thank you, James