The usb has been measured by Dom as taking about 20% of the cpu
to service interrupts, which come at 8000 per second, even when the usb
is idle. USB can be suspended by doing:
echo 1 > /sys/devices/platform/bcm2708_usb/bussuspend
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=7866
However, that prevents use of the USB keyboard. So there is some
interest in perhaps connecting a keyboard using GPIO instead.
Section 2.2 of the Broadcom datasheet says:
"The mini UART is a secondary low throughput UART intended to be used as a console."
Anyone know how difficult it would be to rig this up?
