MicroNova Mercury Board - Questions Before Purchase

[The_PCB_Guy]

Regarding the device discussed here: https://www.eevblog.com/forum/buysellwanted/fs-mercury-dip-fpga-module/

@mark2112 I am considering purchasing this board but after reviewing the schematic I have a couple of questions:

• Is there a complete BOM publicly-available, or is that proprietary?
• For the analog-to-digital conversion I see you use an MCP3008, which is a 5V 8-channel device with an SPI output. Is the FPGA tolerant of the higher voltage output from this ADC (ADC_SCK, ADC_MOSI, ADC_CSN)? I see what appears to be half of a level-shifter for each of these lines (Q2-Q4 with R13-R15) but I do not see any other resistors that I would expect in a standard logic-level translation circuit. Additionally the gate of the NFETs are connected to the HV side, not the LV side as I would have expected. What am I missing?

I'm not sure if mark2112 is even still active here but thought I'd give it a go.

Thank you,
Matt

[The_PCB_Guy]

Many thanks for the suggestion. I had actually looked at the Cmod A7-35T board (comparable in physical size and shape to the Mercury) during my search. The only concern is that I plan to design a board around an FPGA and I would like it to have the footprints for the FPGA on-board, but also have the DIP headers to allow the module to be plugged into it. Once the design is complete and functioning I will populate the FPGA circuitry on my board and remove the module. Therefore, I must be able to duplicate much of the circuitry from the module on my motherboard. Unfortunately it appears the Xilinx XC7A35T only comes in BGA packages, which I currently do not have the technology to populate. It's a pretty dumb reason, I know, but for my project this is more important than the number of logic elements. I do not anticipate my program will be all that large, so the Mercury board should be sufficient. I also have experience with the Spartan series of FPGAs, so the Mercury was an obvious choice to begin with. Additionally I really need the 8 ADC channels that are built-in, whereas the Cmod board only has two. I know I could probably put in an external ADC but why bother if there's a board with it already built in that would still suit my needs?

I am not set on the Mercury, per se, but it seems to be the best choice for my project at this point.

Also, to mark2112, ignore the second question. I figured out the level shifting.

[The_PCB_Guy]

All of my development has been based around a 50MHz clock, if that's what you're asking. Once again I have experience with the Spartan, so that is my preferred series at this point.

This is a personal project, not a professional one, so I'm not concerned about cloning. In fact it will probably be open source eventually.

[accelc2018]

One potential candidate would be the Mimas Spartan 6 FPGA board. It has FPGA in SMD package, not BGA. Nots sure about running 50MHz signal over the headers though. I guess it could fit your use case.