Date: Wed, 18 May 2016 19:19:35 +0200 From: Hans Petter Selasky <hps@selasky.org> To: Karl Denninger <karl@denninger.net>, freebsd-usb@freebsd.org Subject: Re: Oddity with ugen Message-ID: <0442915e-8020-b521-3dd5-29c9937cd204@selasky.org> In-Reply-To: <694e8b6a-2607-ff4e-58ea-53d544ee4e52@denninger.net> References: <b24c5a9a-cb18-c014-75ab-9b923853a70c@denninger.net> <46bd6efe-5335-f659-0b07-5107b0e9a326@selasky.org> <af57a994-2e7a-c0d0-1d84-a333c2b2096b@denninger.net> <b04006da-8b3b-7daa-e8d0-0cea8d1583ed@selasky.org> <8dfad53f-e8a6-68b7-37e2-d5cd95768ceb@denninger.net> <10288d18-6da5-f5e8-e8ec-57d59b32ca7a@selasky.org> <694e8b6a-2607-ff4e-58ea-53d544ee4e52@denninger.net>
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On 05/18/16 18:57, Karl Denninger wrote: > ~620ms > > Rather consistent.... note that the device itself, however, is a > power-line (X10) interface and thus the actual timing of a command that > can be sent (the bits are clocked during the zero-crossing of each 60hz > cycle) is approximately this figure. > > This is an "orphan" device (X10 CM15) and thus there's zero manufacturer > support available for it. Hi, From what I know, there is no USB magic about these intervals. Did you try to run some ethernet traffic, like "ping" while running your test application? The DWC OTG uses a ring buffer for data reception from all endpoints. It is connected to a HighSpeed transaction translator USB HUB chip on the RPI2. The external USB HUB also has some internal memories, though I would think they would get wiped after that many milliseconds. The best way to figure out would be to connect a USB analyzer, like the Beagle one, to see if the traffic is really on the line. An oscilliscope might do too for 1MBit/s traffic (USB LowSpeed), just to figure out the length of the data. --HPS
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