2 MBytes/sec using HID

I'm not an expert, but what I remember, HID can never transport 2 MB/s ! Stef

If you are using the FX2 you can use their driver and API and achieve higher data rates than 2MB.

What exactly are you trying to do?

Thanks for the reply

The data will be streamed continuously from an X-ray line scan array. I was considering HID to avoid the cost of the Jungo WinDriver - the evaluation copy expires after 30 days I think. This is a low volume application and the development cost is significant.

What is the Cypress driver you referred to? Will it do isochronous transfers?

Arthur

Arthur.. I jsut completed a few projects using the FX2 and the CYUSB driver they supply for free. They have an API (cyapi) which makes it relatively easy to do Interrupt, bulk and iso transfers. There is information about it on their website. You can also get a neat littel development board from bitwise systems to get started right away. It has all of the pins on the FX2 broken out to connectors.

There are several issues here. One is you will have to provide a full speed configuration that cannot meet 2mbytes per second, all high speed devices must fall back, even if they don't do anything, so the user can be told about the problem.

Another is HID. It is not restricted to a particular bus speed; it is a higher level protocol. However, it is a horrible, complicated protocol. I would recommend using some bulk protocol, where you can find an existing winxp driver.

The final is using interrupt transfers. You can do what you want, by specifying how many transfers per microframe. You must not NAK if you are trying to send more than one packet per microframe. You can also transfer up to 1024 bytes per transfer.

Good Luck, Steve

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