[Ilugc] Serious Problems With USB Controller in Raspberry Pi
- From: mohan.tux@xxxxxxxxx (Mohan Sundaram)
- Date: Wed, 6 Feb 2013 14:02:36 +0530
On Wed, Feb 6, 2013 at 1:34 PM, Siji Sunny <sijisunny at gmail.com> wrote:
It seems like the usb controller used* *in Rspberry pi SOC (Broadcom
BCM2835) has some serious issues , since it can only supply low amount of
current to its USB devices (Approximately 140 mA). This will cause
continues restart of RPI specially while connecting USB Network Card, USB
Modem or GPS devices.
From what I've read, it is an issue of the USB on the chip w.r.t to
power draw. Powering on by USB gives 500mA while the Model B needs
700mA at peak. So a 1A power source is recommended instead of the PC
powered mode. Higher power draw by the USB causes the thresholds to
falls for the internals and thus the reboot. To avoid this, polyfuses
have been used on the board to restrict the power draw to 140mA.
I had flagged the same problem as USB wireless did not seem to work
well (speed lags) and traced it to the possibility of low power draw.
I tried a powered USB hub and the RPi gave problems in identifying the
device.
My streaming media problem got solved by dedicating a router (54Mbps)
for my link between the RPi and the server. The buffering disappeared.
I believe the ModelA has been released and draws 300mA peak. This may
give more power to the USB than before.
-- Mohan Sundaram
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