USB 3.0 Controller

[olsenn]

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!

[Simon]

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

[T4P]

http://en.wikipedia.org/wiki/USB_3.0#Standard-A

USB 3.0 connectors are generally backwards compatible, but include new wiring and full duplex operation

[krenzo]

The B plug is definitely not compatible between USB 2 and 3.

[PA0PBZ]

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.

[olsenn]

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.

The 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.

[PA0PBZ]

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.

True, but that is not a limitation of the host interface, it's more the construction and the FPGA used.

[joelby]

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.

[Erwin Ried]

The B plug is definitely not compatible between USB 2 and 3.

Yes, 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).

[Psi]

The B plug is definitely not compatible between USB 2 and 3.

Yes, 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).

Yeah, 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 is only forward 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.

[krenzo]

Thanks for clearing that up.

[amyk]

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.

[Simon]

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.

and 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

[Psi]

I've had 40MB/s off USB2.0 once. It does happen, just not predicable

[T4P]

I've had worse than 20MB/s ... it happens to laptops 
Must be the harddisk in question

[Stephen Hill]

If you want a USB 3.0 Controller for any future projects then Cypress do one:

Cypress EZ-USB FX3
http://www.cypress.com/?id=3526

[slateraptor]

If you want a USB 3.0 Controller for any future projects then Cypress do one:

Cypress EZ-USB FX3
http://www.cypress.com/?id=3526

The BGA only package and steep price point make it a painful (albeit only peripheral) option on the market last I checked.

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.

Complete agreement. I just don't see hacking a Logic16 as being feasible; it would require a complete hardware redesign and software update.