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MSP430F5522 USB BSL via PUR button on boot fails if held too long

Reza Naima95461
Intellectual 280 points
Other Parts Discussed in Thread: MSP430F5522

I've implemented the same interface as found on the eval board on an MSP430F5522

Once the button (S4 in the example above) is pressed, after about a second, my windows 7 computer shows a message stating that enumeration failed.  If the USB is not connected and I press S4 and turn on the device, it is battery powered and thus skips the bootloader and goes to the main application, thus the USB must be plugged in.  If I turn it on instantly after pressing the button, it works fine.

Any idea why this is happening?  I feel a bit embarrassed having to tell my customers "you have to push the button and then turn it on really fast" as to why the upgrade is failing.

Thanks,

Reza

  • 0
    Guru 227245 points

    I can only guess... (no personal experience with the USB MSPs).

    But as I see the schematics, pressing S4 connects PUR with the LDO. But it also connects LDO to D+. If the MSP is off (not powered by the LDD/VBUS but by external power) this may cause the USB host to 'detect' a device - which is of course not responding.

    You should connect PUR with VCC if the MSP isn't powered by VBUS. Or (if the device is USB powered) you need to push the button right before and while connecting to the host.

    Agian, it's not a personal experience, but only what I can deduct from datasheet, users guide and generic experience.

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