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Last Post 18 Dec 2007 02:32 AM by  malcolm.hartnell@signalrecovery.com
USB Device Problem in MCF5485???
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rishikeshbs@yahoo.com
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27 Sep 2007 03:53 PM
    Hi,

    I have been trying to get the USB device working on the processor. I followed the instructions in the Ref. Manual (Rev 4) to intialize the USB device controller. However, when I connect the device to the USB host (PC) an interrupt to indicate that Reset Stop Signalling doesnt occur. Shouldnt it occur?? On the other hand when I do read the USBISR register it contains the following:

    1. When I plug the USB cable after the processor starts running the ISR indicates MCF_USB_USBIMR_SUSP bit as set.
    2. When I keep the USB cable plugged in the system and when I restart the processor the ISR indicates MCF_USB_USBIMR_SUSP and MCF_USB_USBIMR_RES bits set.

    But never with RESET STOP bit set. Shouldnt the USB device interrupt when it is connected to the host with MCF_USB_USBIMR_RSTSTOP bit set?

    Can anyone please clarify me on this.

    I have a fire engine and a base board with the following details:

    1. The Fireengine ETX- SOM has a White Sticker with 1000050+B written on it.
    2. Also has this written on the silk screen. PCB 1000266 REV A
    3. The base board is a 548xEVB with 800000245 REV B white sticker.
    4. The processor is a PCF5485CZP200 L14S QAA0450.

    I did the rewiring such that USBVDD and USBOSCVDD would now be powered by 3.3v by following the instructions on PCN 297 Hardware Change notice.

    Are there any other wiring issues or Silicon issues which I am not aware off??

    Thanks,
    Rishi
    malcolm.hartnell@signalrecovery.com
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    --
    18 Dec 2007 02:32 AM
    Hi Rishi,

    I queried Freescale about a comment in their list of errata concerning a problem with the USB controller on the MCF547x/8x processors (34. USB Device Controller May Lose Data in FIFO RAM). I received their reply today.

    Quote:
    If the USB is going to be used to plug into a generic USB tree (e.g. PC with other unknown USB peripherals), then there will be no way to guarantee that there will not be a problem.

    Workarounds are not acceptable at all, so it's HIGHLY recommended to use an external USB controller or, for example the new MCF5445x as another option.


    So, unless the device is going to be the only thing plugged into the PC's USB, you should not use the internal controller. Freescale are supposed to be sending me a presentation that explains more fully the problems with the USB and then I will decide how I will proceed but I don't have much confidence with their ability to make a working USB controller.

    Regards,
    Malcolm
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