On Sun, 13 Jan 2008, Vijay Ramamurthi wrote: > hi, > I am a newbie here, > I am trying to send 64 byte packets from a linux host into a device at > the rate of 4000 packets/second > not sure how many frames does it translate to.
There are 1000 frames every second. Thus you are trying to send 4 transactions (not packets -- each transaction involves at least three packets) per frame, on average. More importantly, since this device appears to be running at high speed, you are trying to send one transaction every 2 microframes on average (there are 8 microframes per frame). > The device hiccups..but keeps going.....quite a bit of NYET and PING > transactions in between.. > but the eventually the host controller just gives up trying to send > packets...not sure why? How do you know the host controller has given up? Maybe the device has given up instead. Have you tried using usbmon (see Documentation/usb/usbmon.txt) to track the data flow? > its a 2.0 system > > ANy idea whats the limit on the frame rate? > n linux..i am using a ubuntu system on the host side Your question is meaningless. There are always 1000 frames per second in USB. That's the frame rate; it is fixed by the USB specification. > ADDENDUM > ******************* > > it is a bulk endpoint > i submit one URB per packet > and the device is a modem, packet deliantion is critical Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
