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K60 and K70 USB Question: True high-speed operation (480 MBps)

Question asked by Gary Kercheck on Feb 3, 2012
Latest reply on Jul 19, 2013 by vladimir khusainov

Hello Freescale Forum,

I have a TWR-K60 application that needs to transfer data at a high, fixed rate over USB.  I seem to be hitting a wall at around 2 MBps (megabits per second) and would ideally like to see 5 MBps or more.

I am using the CDC example project "USB_device" with the "Freescale_CDC_Driver_Kinetis.inf"  file configuring up a virtual COM port on the PC side.  I very much want to stay with this device class as it is straight forward and works with virtually any Widonws XP/ Win 7 system.  I know an audio type device with isochronous exchange can provide more throughput but I was hoping to avoid that complexity and don't want to risk dropping frames.

I know that on the hardware side a USB PHY chip is required to realize tru high-speed (480 MBps) operation.  The TWR-SER2 ehhanced serial module provides this.  We have a very helpful Freescale rep. who has a TWR-SER2 board on order for us.

On the software side, the sample CDC driver is working very well and I was even able to modify the BULK endpoint to use 64 byte packets versus the 32 byte packets it was set up for.  My question is, can I use a modified version of this driver to make high-speed BULK USB function properly?  I would have to change the packet size to 512 bytes at a minimum.   Would there be changes required on the Windows side as well?

Any advice appreciated.

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