USB 3.0 Controller - Page 1
Forum section: electronics / beginners

author: olsenn
author_rank: Frequent Contributor
timestamp: July 16, 2012, 04:04:43 pm
content: I was just wondering how difficult it would be to modify a Logic16 logic analyzer to use USB3.0 instead of its default USB2.0? I familiar with FTDI USB-to-UART controllers and things like that, but I am not sure how direct USB devices like this work and if the USB 3.0 transfers the same data (bit-compatible) just at a higher baud rate?If hacking a change into something like this won't be easy I may try to create a logic analyzer from scratch... I've been dying to use my FPGAs for something anyhow, haha, except I probably am not skilled enough to make decent software for it. I know TI has several IC's available that they call "USB 3.0 Controllers", but I haven't looked into how they work exactly.Thanks in advance for the input!

author: Simon
author_rank: Unknown
timestamp: July 16, 2012, 04:27:44 pm
content: the usb3.0 connectors have 4 or 5 extra wires so I don't think it is just a case of reprogramming. It's a different ball game. Basically USB2.0 with alternative USB3.0 available

author: T4P
author_rank: Super Contributor
timestamp: July 16, 2012, 04:36:03 pm
content: http://en.wikipedia.org/wiki/USB_3.0#Standard-AQuote

author: krenzo
author_rank: Regular Contributor
timestamp: July 16, 2012, 07:07:23 pm
content: The B plug is definitely not compatible between USB 2 and 3.

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 16, 2012, 08:28:31 pm
content: Even if there was an easy way to change the USB 2.0 interface to an USB 3.0 (I'm sure there isn't), the thing is not magically going to change the speed it is communicating. So if you want the benefit of USB 3.0 you will have to change the complete design, or in other words: make a new design.Even then, what are you trying to get out of this? Since most of these LA's have a built in memory buffer, you're not going to increase the sample speed by just changing the speed it communicates with the host.

author: olsenn
author_rank: Frequent Contributor
timestamp: July 16, 2012, 08:37:53 pm
content: QuoteThe FPGA can only buffer so much before the capture has to end, and at high sampling rates it doesn't take long to do. Furthermore, most LA's can sample only at around 100MSa/s at most, which I suppose could capture a 50MHz signal, but realistically it needs to be oversampled quite a bit, so I would say it probably caps out at around 20MHz or so, and that's with only two channels active... 10MHz for four channels; even an Arduino has a faster clock speed than that.

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 16, 2012, 08:45:24 pm
content: Quote from: olsenn on July 16, 2012, 08:37:53 pmTrue, but that is not a limitation of the host interface, it's more the construction and the FPGA used.

author: joelby
author_rank: Frequent Contributor
timestamp: July 17, 2012, 12:52:24 am
content: I haven't seen many FTDI-esque serial-to-USB bridges for USB3.0, so most of the USB3.0 chips are just PHYs. You can connect these to an FPGA, but you'll need to implement the other transport layers on the FPGA. Performance ought to be much better, but development will be much harder if you're doing it all from scratch. It'd be a fun project, though! I spent a bit of time looking into it a while back.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: July 17, 2012, 01:15:12 am
content: Quote from: krenzo on July 16, 2012, 07:07:23 pmYes, it is, I have a hardisk with that connector and you can use the same connector with usb 2.0 micro connectores (just the part that fits).

author: Psi
author_rank: Super Contributor
timestamp: July 17, 2012, 01:33:24 am
content: Quote from: Erwin Ried on July 17, 2012, 01:15:12 amYeah, It depends if you're talking about the socket or the plug.USB 3.0 A plug is backwards and forwards compatible.USB 3.0 B plug isonlyforward compatible (you can't plug a USB 3.0 B plug into a USB 2.0 B socket)Both USB 3.0 A & B sockets are forward and backward compatible.

author: krenzo
author_rank: Regular Contributor
timestamp: July 17, 2012, 03:02:34 am
content: Thanks for clearing that up.

author: amyk
author_rank: Super Contributor
timestamp: July 17, 2012, 08:48:19 am
content: USB 3.0 is much more stringent in its physical requirements as the signaling frequency is in the same range as SATA and PCIe, so it requires more careful design to meet the spec. 1.1/2.0FS is extremely lax in comparison.

author: Simon
author_rank: Unknown
timestamp: July 17, 2012, 08:50:33 am
content: Quote from: amyk on July 17, 2012, 08:48:19 amand no surprise. I found tat USB2.0 gets 240 Mbps not the claimed 480 Mbps when communicating with a SSD which was obviously faster than the USB interface

author: Psi
author_rank: Super Contributor
timestamp: July 17, 2012, 09:30:42 am
content: I've had 40MB/s off USB2.0 once. It does happen, just not predicable

author: T4P
author_rank: Super Contributor
timestamp: July 17, 2012, 04:33:11 pm
content: I've had worse than 20MB/s ... it happens to laptopsMust be the harddisk in question

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 18, 2012, 12:00:31 pm
content: If you want a USB 3.0 Controller for any future projects then Cypress do one:Cypress EZ-USB FX3http://www.cypress.com/?id=3526

author: slateraptor
author_rank: Frequent Contributor
timestamp: July 18, 2012, 06:33:06 pm
content: Quote from: Stephen Hill on July 18, 2012, 12:00:31 pmThe BGA only package and steep price point make it a painful (albeit only peripheral) option on the market last I checked.Quote from: amyk on July 17, 2012, 08:48:19 amComplete agreement. I just don't see hacking a Logic16 as being feasible; it would require a complete hardware redesign and software update.