how to connect FPGA with linux

Question

Hello,

I was thinking about how to directly connect a FPGA to linux (iMX233 board based on the olimex design).

I have two ideas:

- SPI (maybe with MCU for parallel interface with FPGA and basic data processing).

- External "address translation" system and use few bytes of memory space for some universal parallel interface.

I'm doing it just for myself (universal board for fun) so no special purpose.

Anyone with experience in this? Any tips?

michaelkellett · Answer

On real designs I often do both and a bit more: SPI with a couple of extra handshake lines memory interface, sometimes with full address bus but often with most of the address lines missed off leaving perhaps A0, A1, A2 and A19,A19 and a couple of chip selects - this saves a lot of pins and tracks but if you do blocks of sequential reading or writing it can be very fast. It's always good to have a few additional control signals which will save your bacon as the design evolves over time. I quite like UARTS as well, I've taken to adding debug UARTS to bigger FPGA designs so I can just connect a PC to them via one the FTDI USB to UART bridge 'wires' and talk to them. MK

johnbeetem · Answer

Hi Tomas, You might also try asking this in the http://www.element14.com/community/groups/fpga-group . Here's my answer: the beauty of FPGAs is that you can design the FPGA to match whatever interface(s) the board or SoC has available. The easiest IMO is if the SoC has an external memory bus: the FPGA simply acts as read/write memory. You can also do SPI and/or I²C. SPI is faster and simpler than I²C. If you're really ambitious, you can do PCI or even PCI express. ValentF(x) has a hardware/software co-design approach for their LOGI boards that might be helpful: http://www.element14.com/community/groups/fpga-group/blog/2014/10/09/hardwaresoftware-co-design-with-the-logi-boards

how to connect FPGA with linux

Top Replies