Electronics > FPGA
Planning/design/review for a 6-layer Xilinx Artix-7 board for DIY computer.
nockieboy:
Okay, it's been a while due to work and life, but here's a quick update. Features and schematic are almost pinned down now, I just need a little feedback on the USB hub that I've included below. I'm unsure about USB_HUB_5V and USB_HUB_ID signals from the USB PHY - I think I'll just strap USB_HUB_5V to 5V and leave USB_HUB_ID floating, but if anyone has any thoughts or can spot any errors, let me know! :)
The idea is to provide four USB 2.0 ports to the FPGA, so a soft-core CPU running a capable operating system can access a USB keyboard, mouse, storage etc. A more direct method of connecting a USB keyboard to a non-USB-capable operating system (my 8-bit Z80 computer, for example) will be provided via a peripheral board (connected via a PMOD), which I might design later if I ever get round to it.
Schematic for the USB hub is attached.
I haven't had time to mess with Vivado much yet or start working on the AXI/BrianHG_memory_controller interface. ::)
dolbeau:
--- Quote from: nockieboy on March 23, 2023, 11:55:50 am ---The idea is to provide four USB 2.0 ports to the FPGA, so a soft-core CPU running a capable operating system can access a USB keyboard, mouse, storage etc. A more direct method of connecting a USB keyboard to a non-USB-capable operating system (my 8-bit Z80 computer, for example) will be provided via a peripheral board (connected via a PMOD), which I might design later if I ever get round to it.
--- End quote ---
Do you need the 480mbps of USB 2.0?
For keyboard/mouse and (slow...) storage, USB 1.1 could be enough. There's (at least) a OHCI-compliant soft-host available, which can do 1 to 4 ports with just the ESD/TVS stuff externally, plus the VBus regulation if you don't want to force the use of a self-powered USB hub. You only need a single differential pair of I/O per port, and it will work with any OS that has an OHCI driver. I've used it for keyboard/mouse/basic storage under NetBSD/sparc on a '94 SPARCstation 20.
asmi:
--- Quote from: nockieboy on March 23, 2023, 11:55:50 am ---Okay, it's been a while due to work and life, but here's a quick update. Features and schematic are almost pinned down now, I just need a little feedback on the USB hub that I've included below. I'm unsure about USB_HUB_5V and USB_HUB_ID signals from the USB PHY - I think I'll just strap USB_HUB_5V to 5V and leave USB_HUB_ID floating, but if anyone has any thoughts or can spot any errors, let me know! :)
--- End quote ---
ID pin of the PHY is only required for USB OTG support, you can leave it unconnected since we only want to support USB HOST configuration. Also check the "Hardware Checklist" documents for your USB hub and USB PHY parts on Microchip website - they have a lot of useful information for applications.
asmi:
Well, it took quite a bit longer than I anticipated due to me not having much of a spare time, but I've completed a board design I envisioned. It turned out to be quite a monster - 10 layers (as opposed to 6), via in a pad, and 150 x 120 mm in size, it's got onboard USB-JTAG as well as JTAG TagConnect footprint, also 1G Ethernet and an HDMI out, everything else is routed out to 3 high speed connectors - one with 4 MGTs and some GPIO, another one with almost a full bank of GPIO, and a third one with a full IO bank (50 balls) routed as length-matched differential pairs (and 2 single ended signals). 3D renders and schematics (updated schematics are posted in a later post) are in attachment for those curious what it looks like. I'm still doing some final checks in an attempt to prevent "a curse of the first revision" to strike me again (which usually are futile) before sending design out to manufacturing, so I'm hopeful, but we'll see.
Some stats:
Board size: 150 x 120 mm
Components on board: 557
Layer count: 10
Smallest drill size: 0.2 mm
Smallest trace width/spacing: 0.1/0.1 mm
Total number of connections: 1871
Total number of non-plated holes: 57
Total number of plated holes: 2180
asmi:
Good thing I didn't rush it to manufacturing :phew: Found and fixed a bunch of things. If anyone has some spare time and inclination, please review updated schematics (in attachment) to see if something jumps out on you. UPDATE - see later post in this thread for latest schematics.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version