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Ask HN: How to fake laptop connection via USB
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2 points
by pizu
3630 days ago
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Hope we have some USB professionals here.
I have an external audio sound are device that is USB powered and needs to be connected to PC/Mac/tablet for it to power up.
The device has a built in mixer that offers direct monitoring, I've audio goes from input ports directly to outputs (skipping the PC).
I would like to make the device work as a standalone mixer without the need to connect to a PC. I've connected the device to a USB wall socket/charger but the device doesn't power up.
I suspect that the reason is that the USB charger only sends 5V power but not the data steam (to pin 2 and 3, as presumably PC does).
Does anyone know if it's possible to hack the USB cable or USB wall charger to make the audio device think it's connected to a laptop?
Or phrased differently, what does the device see when it's connected to PC vs a wall charger? |
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Here's a link to start you off with.
http://electronics.stackexchange.com/questions/123172/what-i...
Most usb devices will look for data before thinking about initialising.
Hard way to solve your problem: If you wanted to power it up and set it up for a certain configuration without a PC, you'd probably be best off starting to sniff the usb bus and possibly play back the results (YMMV) with an arduino or similar.
You'd need something along the lines of a bus pirate to do all that https://en.wikipedia.org/wiki/Bus_Pirate
Less Hard Way: Or if you're a software person, you could just sniff the usb bus of a virtual machine, but I imagine that you may miss certain bits of handshaking, then program an arduino or similar appropriately
Easier way: If the device has linux drivers you could hunt down a raspberry pi zero (or a regular one, or beagle bone or any number of other ARM linux boards) and just drive it from that.