Anyone know if there's a standard(ish) for simple mezzanine cards for FPGA boards?
I know about things like FMC and HSMC which are very 'high end' - multi gigabit transceivers, expensive connectors. There's also Arduino, which is simple and low pin count, but everything is designed to talk to a dumb slow Atmega (which usually means putting another Atmega on the mezzanine card and talking via SPI). Or there's Raspberry Pi, but again it's assumes you have slow I/O and things like Ethernet and USB already exist on the CPU board.
Is there anything between the two? Something like an Arduino-scale system but with a $10 FPGA in mind rather than an 8 bit micro or a $1000 FPGA. For instance, an 100M Ethernet PHY which is just the phy rather than a memory-mapped MAC, and so just presents an RMII or SMII interface. Or a USB2 ULPI PHY. Having a microcontroller on the board is OK (USB offload is a useful task), just drinking it through an SPI straw is not.
Any other ideas?