Gerald, You mean a 5VDC adapter which negative is grounded ?
These are dificult to find, at least most of those adapters have only two connectors for the outlet :( OTH. Are there any testpoints for USB D+ and D- on the BBB so I can patch my oscilloscope ? I'm having lots of errors with USB 3G modems (mostly Huawei) and would like to see the eye pattern if posible. My error aren't Babble Interrupts but more like (and reported by others too): [20589.786521] WARNING: at drivers/usb/musb/musb_host.c:125 musb_h_tx_flush_fifo+0x54/0x88() [20589.795094] Could not flush host TX2 fifo: csr: 2103 On Wednesday, June 5, 2013 11:11:35 AM UTC-3, Gerald wrote: > > You definitely need to ground the board properly. A grounded supply is the > best but make sure it is the same ground/power strip as the PC or monitor > that you may be connected to. > > Gerald > > > > On Wed, Jun 5, 2013 at 9:04 AM, Andrew Henderson > <[email protected]<javascript:> > > wrote: > >> On Wednesday, June 5, 2013 6:01:52 AM UTC-4, Shi Bai wrote: >> >>> Hi Andrew, >>> >>> Thank you so much for your detailed answer. It indeed addressed my >>> doubts very well. I believe my Huawei modem is triggering babble interrupt >>> in the initializing stage and seems not only my device, but some other >>> device will trigger it as well. The hot plug fix looks very promising as >>> well. I haven't had a single hot plug issue since the upgrading. >>> >>> May I ask if you have idea now why the mpurate will reduce the -110 >>> error? >>> >> >> Babble interrupts are caused by a noisy signal ("babbling") occurring on >> the USB signal line. The typical causes for this that I have observed are >> improper grounding and static electricity. My guess is that by increasing >> the mpurate, which increases the core MPU voltage, you increase the voltage >> of the USB signal and make it a little bit more tolerant to the conditions >> that cause a babble interrupt. My testing of the babble recovery patch has >> shown me that it isn't perfect. It will recover from the babble interrupt >> once, but then hotplugging will not work. Some examples: >> >> 1. The USB device is plugged in at boot, and a babble interrupt occurs. >> The device will work until it is unplugged. When plugged back in, it is >> not recognized. >> 2. The USB device is plugged in at boot, and no babble interrupt occurs. >> The device will work until it is unplugged. When plugged back in, it is >> recognized and is reinitialized and begins working again. >> >> I think that investigating BBB grounding issues might be the best way to >> go to ultimately address these babble interrupt issues. >> >> Andrew >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > > > -- > Gerald > > [email protected] <javascript:> > [email protected] <javascript:> > http://beagleboard.org/ > http://circuitco.com/support/ > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
