FPGA as a "host" or a peripheral device?

PCB Design
#1

I’m quite curious how others forsee using these FPGA boards - primarily with or primarily without an MCU/CPU?

You see, based on my professional experiences, I have probably developed some biases and could use a sanity check.

With this new board, I’m hoping to (a) test drive the FPGA board, to see if it would be a good teaching tool for interested, but less experienced members of my team and (b) use the board to make something beyond Hello World, in order to get a realistic idea of the workflow & complexity involved with something non-trivial.

Anyway, in the past, I’ve/we’ve used a pretty large range programmable devices (CPLDs, FPGAs), from ~10 USD to ~1000 USD. In all of these cases - even ones that used the NIOS (soft core processor), CPUs or MCUs were always present to do most of the boring stuff that they’re good at.

For example, we happen to require fairly high-speed (typically 1Gbps, plus or minus an order of magnitude) wired Ethernet with both TCP/IP and non-IP traffic. This is all totally doable with an FPGA, but it’s a hassle, adds the development cost and most likely adds to the BOM cost, due to the larger logic footprint and potential use of 3rd party IP. So, for several reasons, the best solutions always seemed to be those with companion processors.

Back to the original question, I’m wondering of whether my CPU/MCU + FPGA experience/perspective is unique, and most users are planning an FPGA-centric configuration. Or, are many users planning to use the FPGA as a compute or high-speed digital interfacing peripheral, with a more conventional processor pumping data in and/or out?

(FWIW, my testbed project will be using a Teensy 3.x - a platform that’s been great for test fixtures.)

How do you plan to use the FPGA board?

Thanks.

#2

Kan,

I too want to see how people plan to use the FPGA board. I myself am more centric on pure digital logic solutions, ie no micro. This is from years of doing digital logic for ASICs and FPGAs.

I think using existing shields such as an RF shield connected to the FPGA makes a great remote data collector. Of course it can be done with a micro as well, but you need to develop both firmware and verilog.

My home projects aren’t usually optimized for cost, but in my professional world cost is very important vs fun stuff at home.

So I also can see both cases being needed, the FPGA is a plugin on an existing MCU platform, and the FPGA board can accept an existing shield, without the MCU.

Most shields do run on 3.3v, which should help simplify a possible variation of a common solution. The Teensy is a nice small platform to connect the FPGA board too.

My FPGA based project:
I have a project that I have been kicking around for a while, is to use an FPGA to collect data via Ethernet with POE without a LAN controller. I spent my early days designing Ethernet MACs for ASICs, so a simple 64 byte UDP packet is all I need to collect data to be sent back to a linux system. The plan is to do it without a micro, and use a very minimal 10 base-T MAC and associated electronics, and powering it off the Ethernet cable.

Mick

#3

Unless you need 10 mbps speeds, I’d recommend using SLIP/PPP with a serial connection, but still over CAT5 or whatever, with the extra pairs used for power. Same packet, much simpler interface.

#4

Thanks BobC, will take a look atSLIP/PPP.