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USB COM port (CDC) device very slow at initializing depending on PID (MSP430F5659)

Derek I
Prodigy 100 points

I'm using the 4.20 USB stack (and the examples for reference) and I've created a USB composite device (CDC and MSC). My machine is running on Windows 7. I've found that if I use the PID given in the example for 'C1_LedOnOff'  (0x0300) the device comes up in device manager correctly and the COM port is able to be opened almost instantly in TeraTerm for example.

If I use another PID, (given by TI) 0x03DF, it will show up in device manager instantly as well but it will not show up in TeraTerm as an open-able COM port until ~1 min and 40 seconds later every time I plug in the device. Why is this the case? In both cases I've used the provided descriptor tool. I would use the example PID 0x0300 but then my device would not also be a MSC device, it would only be a CDC device. I also have to install the driver manually (using the 'Have Disk' option) with the inf file created with the descriptor tool but I think that is expected.

  • 0
    Guru 243680 points

    The different PID itself does not make any difference, but the different .inf file might do. Are there any differences in your .inf files, except for the PID?

    Such a delay sounds as if Windows is searching the internet for a driver (update), but this should not happen at every plug-in.

    When exactly do you need to manually install the driver? Every time you plug it in?

    Do you get any "unsigned driver" warnings?

  • 0 in reply to Clemens Ladisch
    Prodigy 100 points

    I don't actually need the .inf file when I am using PID 0x0300, I can just change the PID in descriptor.h because that driver is TI's driver that was already installed I believe. The only differences between the .inf file for PID 0x0300 besides the device list are the following lines:

    [Version]

    .

    .

    .

    CatalogFile=MSP430_CDC.cat

    [DefaultInstall]
    CopyINF=msp430_ti_signed.inf

    Those lines are not included in my .inf file.

    I only need to manually install the driver the first time I plug it in when I'm using a PID that is not 0x0300. I do get the unsigned driver warnings every time though.

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