LVDS to PCIe bridge solution

[cblackburn]

Hi All,

First time posting here after watching the YouTube series for ages. It's good to find a corner of the internet filled with like minded EE Geeks

I've got a problem with a board I'm designing that I was hoping you guys might give some insight into. I have a chip which is generating ADC data at a fast rate and sending that data over an LVDS link. Specifically, there are 8 pins in 4 differential pairs. Two pairs are data and the other two are clock and "frame clock". I have attached a cutout of the datasheet for clarity. These are clocked at up to 450MHz DDR (so 900 Megabits). I need to get this data into our controller so I can send it on/process it. We are aiming for a Raspberry Pi CM4 as our host computer so the only interface I have that's fast enough for this would be the PCI Express Gen 2 1x link. This means I need something which can take the LVDS in and act like a PCIe device which can forward the data onto the host.

Now, the usual answer for something like this would be "use an FPGA". But, before I go down that rabbit hole this feels like the sort of thing where there *might* be a single chip (or collection of chip) off-the-shelf solution that I could use. I always try to follow the old adage of not reinventing the wheel. Despite much Googling I've not been able to turn up anything so, does anyone have experience with this? Or, is it time to fire up the VHDL?

If I am going down the FPGA route what would people recommend as a chip which would be "just enough" to accomplish this (as always, beancounters are asking to keep the BOM cost down). It's been a while since I was in the FPGA space, back then it was "Xilinx all the way" but I hear good things about Lattice Semi and a few others.

Thanks for your help

Chris

[mvs]

Perhaps you can use CSI2 interface of RPi for your task. The documentation is however under NDA (Broadcom).

[cblackburn]

Thanks mvs, that's not a bad idea at all. Some research would indicate that CSI is basically LVDS but with some specific data layer framing requirements. I am able to influence the LVDS data structure so this might work.

Unfortunately, to get hold of the MIPI CSI-2 standard documents you have to pay a minimum of $8,000 per quarter! Yikes. Hopefully I can piece together enough information through googling and/or experimentation.

Chris

[amyk]

Code: [Select]

MIPI Alliance Specification for CSI-2Search for that and you will be enlightened