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MSP430 USB PLL Settling Failure

Philip McCorkle80008
Prodigy 20 points
Other Parts Discussed in Thread: MSP430F5522, MSP-TS430PN80USB, MSP430F5529

What would cause the PLL to fail to settle? I'm using the MSP430F5522 with a custom made PCB. I know the PCB design works because I've been using it without any problems - until now. I'm using the examples from the USB Dev Package API stack. My USB device is not being recognized by the computer. When it is connected to my programmer board (launchpad), it just sits there and does nothing when I run the program. If I run my device standalone, it takes about 10 seconds fro my computer to recognize it, but it quickly says the device is not recognized. I hear the "dun-DUN" (connect) sound, quickly followed by the  "Dun-dun" (disconnect) sound.

When I debug the program, I've tracked down the problem, I think. In the function call "USB_enable()", USBPLLIR never evaluates to being  0 (PLL settling failure?) in the do{ }while (USBPLLIR != 0); line. What would cause this? What would cause the USBPLL to never settle? Crystal problems?

  • 0
    Genius 4680 points

    > I'm using the examples from the USB Dev Package API stack.
    > What would cause the USBPLL to never settle? Crystal problems?

    1) Crystal frequency / port
    TI's USB Dev Package supposes their target boards, MSP-TS430PN80USB or MSP-TS430PZ100USB. On these board, a 4MHz crystal is attached to XT2 ports. If your board mounts a crystal of other frequency, or if the crystal is connected to XT1 ports, you have to tune the source so as to match to your board.

    descriptors.h
    #define USB_PLL_XT        2                  // Defines which XT is used by the PLL (1=XT1, 2=XT2)
    #define USB_XT_FREQ       USBPLL_SETCLK_4_0  // Indicates the freq of the crystal on the oscillator indicated by USB_PLL_XT

    USBPLL_SETCLK_4_0 is defined on msp430f5522.h of your compiler include file.

    2) Chip revision
    On a rev A silicon of MSP430F5529, attached to MSP-TS430PN80USB board, I've seen PLL start-up failure. It was solved by replacing the chip to a rev E silicon.

    MSP430F552x, MSP430F551x Device Erratasheet (Rev. J)
    http://www.ti.com/litv/pdf/slaz054j

    Tsuneo

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