3 ms·
If you plug a USB device that consumes more than 100mA into the pi it will likely not power the usb device without a powered hub in between.
by gravitronic 14y ago
If you plug a USB device that consumes more than 100mA into the pi it will likely not power the usb device without a powered hub in between.
- michaelt 14y agoI've checked the RPi schematic [1] and it each of the USB ports protected by a miniSMDC014 rated for 140 milliamps [2] (and taking 150ms to trip at 1.5 A) With two usb devices drawing 140 mA, a total of 280 mA would be consumed, thereby narrowly exceeding the 700mA power budget. Fuses are also typically quite imprecise for obvious reasons - they rely on current heating up metal that melts and breaks the circuit, and you don't want it borderline molten under normal operating conditions! So you may well be able to draw 250 mA per port without the fuses triggering. You'll note the Raspberry Pi wiki [3] has a bunch of bug reports like "Ethernet connection is lost when a USB device is plugged in" attributed to inadequate power supply current. [1] http://www.raspberrypi.org/archives/1090 http://www.raspberrypi.org/archives/1090 [2] http://datasheet.octopart.com/MINISMDC014F-2-Tyco-Electronics-datasheet-58412.pdf http://datasheet.octopart.com/MINISMDC014F-2-Tyco-Electronic... [3] http://elinux.org/R-Pi_Troubleshooting http://elinux.org/R-Pi_Troubleshooting
- gravitronic 14y agoSo, I've got one and am experiencing similar issues.. I believe that right now the "power supply" issue had been used as a blanket response to ethernet/usb issues until people were seeing that problem with an oscilloscope on their power supply and no power supply issues. What seems to be the common conclusion is that it's a bug in the DWC OTG USB driver/firmware: http://www.raspberrypi.org/phpBB3/viewtopic.php?t=9470&p=128799 http://www.raspberrypi.org/phpBB3/viewtopic.php?t=9470&p... et al