Typically, if you want to build an FPGA project inside a PC, you’d need a fairly expensive development board that plugs into the bus. However, [CircuitValley] found some IBM RS-485 boards that are little more than a PCIe board with an Intel FPGA onboard. These are widely avaiable on the surplus market for around $20 shipped. He’s been documenting how to use them.
The FPGA onboard is a Cyclone IV with about 21,000 logic elements and a little over 750 kbits of memory. The board itself has configuration memory, power management, and a few connectors. The JTAG header is unpopulated, but the footprint is there. You simply need to supply a surface-mount pin header and an external JTAG probe, and you can program. Even if you aren’t interested in using an FPGA board, the reverse engineer steps are fun to watch.
The situation reminds us a little of the RTL-SDR — when a device uses a programmable device to perform nearly all of its functions, it is subject to your reprogramming. What would you do with a custom PCIe card? You tell us. Need a refresher on the bus? We can help. Thinking of building some sort of FPGA accelerator? Maybe try RIFFA.
This is pretty cool.
Suprising that they used and FPGA for this, there are many pci-e to rs232 chips. But maybe they don’t have the control signals for the transceiver?
You could call IBM to upgrade your mainframe remotely because they had redundant hardware preinstalled. It was just how they did business.
May not actually be redundant hardware strictly speaking – as the FPGA is flexible it can be pushed to the vicinity of its limits in a variety of ways (or you could argue always has wasted redundant elements that are only required for alternative logic configurations). That flexibility be important and cost effective as depending on the usecase the same mass produced hardware can still do the job. Not sure that applies in this case, but it is certainly possible.
This is excellent news! I’m sure the prices will sky rocket after this but just the work itself is brilliant.
“I’m sure the prices will sky rocket after this”
And they have. Cheapest in UK is now £60 (about 72 Euros).
I would suggest looking at the Sipeed Tang series then instead. Their Tang Mega 60k is a bit more expensive than the now inflated prices on this card but it is much more usable and a better FPGA.
via ebay in australia the cheapest I can find now is $250 + $70 postage from china 🙃
The RTL-SDR doesn’t use a programmable logic device at all, it uses a mass-produced consumer ASIC (RTL2832) that just happens to have the SDR functionality designed in, as Realtek was using it to demodulate DAB and FM radio in software. This way, they didn’t have to implement it in hardware.
The main functionality (demodulating OFDM-based television signals) is baked into hardware as well.
It reminds me more of those FPGA re-use projects:
https://hackaday.com/2020/12/10/a-xilinx-zynq-linux-fpga-board-for-under-20-the-windfall-of-decommissioned-crypto-mining/
https://hackaday.com/2019/11/20/old-cisco-wan-card-turned-fpga-playground/
The original SDR was sold as an (analog) TV receiver.
The similarity being: a repurposed device, enjoying a longer life cycle.
I applaud the effort to reverse engineer the board, but that is not a schematic on his blog, its a lookup table.
He found all the fpga pins and mapped those, what else do you need?
Bought an RME DIGI9636/52 7 years ago for 14,50€ for the same reason. Some day I will find the time to start with the PCB analysis.
Also, Lattice ECP5 FPGAs are all PCIe-capable (single lane), start at $15, and are suitable for your own PCIe-based designs.
I looked for FPGA PCIe evaluation cards for this purpose. The lowest priced was the Versa ECP5 at around $350. Beyond that, $1000+ for eval kits. I’m comfortable with Lattice. Lots of experience with ICE40.
$20 is a steal.
Dollar sign goes before number.
The video comes from Europe that’s why there is this small mistake.
I especially thought that the transmission of the pin by enabling an uart on all fpga pins was brilliant and very creative.