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MSP430F5522 not taking computer USB power

Felipe McCorkle94454
Prodigy 20 points
Other Parts Discussed in Thread: MSP430F5522

Hi, I just want to start off by saying this is probably my fault in that I tried making some kind of custom driver for my device using LabView. I may have messed some descriptor files up or something. Who knows...

With that said, here is what is happening at the moment. I have some example USB programs (from TI) that used to work on my custom dev boards. The computer would recognize the device as a virtual com port, like normal, and everything was happy dandy. Then, at some point I started poking around under the hood, and now my computer doesn't  acknowledge that I even plugged in my device. When I look at the USB voltage for my device, it's ~3.8V on the 5V line, and the regulated 3.3V out of the MSP430 is a measly 0.76V. Nothing is happening on the chip.

However, the odd thing is, when I plug my device into, say my oscilloscope's USB port, it fires up and the program runs like normal. When I give the chip 3.3V directly (without any USB or anything else connected), all is well. What gives? Do I need to uninstall and re-install something? 

  • 0
    Guru 227245 points

    Does any other device still run on this PC USB port? Maybe you broke it.
    What is the targets power consumption? >100mA?
    It's possible that you overloaded the USB hub by an overcurrent that was too much but didn't make it shut down. And now the HUB cannot provide more than a few mA anymore. If so, maybe applying an external HUB with its own power supply will help.
    Another possibility is that the PC is switching the port to power save mode for some reason, and so it won't detect a plugged device.

    Just guesses...

  • 0 in reply to Jens-Michael Gross
    Prodigy 20 points

    Thanks for the thoughtful reply, but I'm afraid that isn't the issue. The USB port(s) works fine, even with current hungry devices. It seems to JUST be this MSP430F5522 device. I haven't tried any other MSP430 variants, but the LaunchPad programmer works, my mouse works, every other thing that I can think of works.

  • 0 in reply to Felipe McCorkle94454
    Guru 227245 points

    Well, if the device runs on a different host, but when you plug it into your PC the bus voltage breaks down, then there msut be a harware error ont eh PC side. That's the only explanation. It can be the USB controller, the HUB, the USB socket, or even the cable. try a different USB cable, and a different USB socket.

    If it were the MSP side, it wouldn't work on a different host (like your scope) too.

    Even if the MSP would put the device into sleep mode, it should at least enumerate first.

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