Honored Contributor
Honored Contributor<div class='quotetop'>QUOTE </div>
--- Quote Start --- USB 2.0 High Speed should be capable of transferring at 480Mb/s or about 60MB/s, but some of that is packet overhead. I'm curious if there are issues sustaining this rate with a NIOS II? We are planning on two: a host running full speed in bursts, and a peripheral running continuous at about 1/3 speed.[/b] --- Quote End --- The theoretical maximum transfer rate bulk packets under USB 2.0 is about 53 MBytes/sec (Thirteen, 512-byte packets per microframe [125 uS] = 53.248 MBytes/sec). However, so far, I have never been able to transfer more than ten, 512-byte packets per microframe (40.96 MBytes/sec) when transferring a very short data burst of 64 KBytes. This measurement was done on a 3 GHz Pentium 4 PC running Windows 2000 as the host and a Cypress USB development kit as the USB 2.0 device that counts the number of packets that were passed every microframe. It's possible that the measurement might have gone up slightly (11 packets per microframe) when using a slightly faster PC running under Windows XP. However, transferring a small burst of 64 KBytes is one thing, but maintaining a sustained transfer rate of ten packets per microframe is something else entirely. I don't have a good way of measuring the maximum sustained transfer rate over USB 2.0 for a particular host PC. If anyone knows of a good USB 2.0-enabled device (e.g. disk drive) that has a high sustained bulk data transfer speed, I would like to hear about it. <div class='quotetop'>QUOTE </div> --- Quote Start --- For our project, we are in a similar situation, and are using USB 2.0 OTG High Speed, which will be implemented in an FPGA (IP). We are going point to point, not requiring a HUB, but an OTG Host will support a HUB.[/b] --- Quote End --- We are considering purchasing some FPGA IP for implementing a USB 2.0 OTG capability. Can you tell me which IP vendor you are using and why you chose that vendor? One of the reasons we have typically stayed away from IP of this magnitude is cost. Can you give me an idea what the cost was for your IP? Which PHY interface are you planning on using with your IP? <div class='quotetop'>QUOTE </div> --- Quote Start --- Anyone know of a USB 2.0 OTG uClinux driver?[/b] --- Quote End --- I wish I did. If you find one, let me know. ;-) Sincerely, Brad S.
