Electronics > FPGA

Planning/design/review for a 6-layer Xilinx Artix-7 board for DIY computer.

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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.

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