Rockbox General > Rockbox General Discussion

How is a USB connection detected on H300?

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W. Irving:
I have a half dead H340 (a more detailed topic is available at Misticriver) which thinks it's perpetually connected via USB, both in rockbox USB bootloader mode, and stock firmware.
My question, how does the software know there is a USB cable connected? Does it receive a signal from the USB controller?

LinusN:
The 5V on the USB port is (via a transistor and a few resistors) connected to the GPIO39 pin on the CPU. If the CPU thinks that USB is connected all the time, either the input port is broken, or the transistor.

W. Irving:
Then I suppose ~something~  :-[ happened to the transistor that has made it constantly conduct. Tack!

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