Is syncronizing 2 isochronous signals possible on 2 different hubs? on the same hub? I need to make sure that data from 1 USB port and data from a different USB port arrive at my circuit at the same time (to within 1us). For now I am only using Full Speed.
thanks Ted
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You need to read the spec for usb 2.0 at www.usb.org But here are some quick comments.
USB is a serial bus, so if the devices are on the same bus (and full speed), each bit is 84 ns, so your packet would have to be less than 12 bytes (including overhead) to be less than 1us. Probably not possible or useful. Might be possible at high speed.
You might be able to use two root hubs, so you have two usb busses, but then they will need to be somehow synchronized... possible but not easy.
Iso is an unreliable send, so you are not guaranteed that both packets will always arrive and arrive with good data. The only guarantee is bandwidth.
Regards, Steve
__________________________________________ Steve Calfee -- embedded systems consultant [EMAIL PROTECTED]
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