fpga4fun.com

Hi there,

I was wondering the max/avg xmit/recv speed for the USB interface on the Dragon board? (Or details of the EZ-USB chip.. which one is it?)

Thanks!

EZ-USB is capable of 8Mbits/s (depending of the PC you're using), see http://www.cypress.com/cfuploads/suppor ... alysis.pdf

But Dragon is not enabling the USB ping-pong buffers by default. So it gets slower speeds. Here's what I got in burst mode using my machine (XP) and the current defaults:
Transmitted 1310700 bytes in 2.58 seconds (0.51MBytes/s, 4.06Mbits/s)
Received 1310700 bytes in 1.78 seconds (0.74MBytes/s, 5.88Mbits/s)

I just enabled them, and voila
Transmitted 1310700 bytes in 1.30 seconds (1.01MBytes/s, 8.05Mbits/s)
Received 1310700 bytes in 1.34 seconds (0.98MBytes/s, 7.82Mbits/s)

So very close to 1Mbytes/s
To make that available, I would have to add an option into FPGAconf. Let me know if you need that.

Certainly, that would be useful. Of course, I'll let you know next month, see if I have enough cash floating around yet to buy a dragon
So I take it the USB interface is reprogrammable (i.e. w/8051 assembly)?
That's pretty cool..

The EZ-USB core does all the hard work, the 8051 assembly is there to enable a few things, and move the data where you need it (the FPGA here).

I made a new page this weekend (see http://www.fpga4fun.com/board_dragon_8051.html) but it's very raw right now, I'd need to publish a few examples to explain how to use the 8051.