Hi All,
I'm doing some digging around to figure out some of the interactions
between the OMAP3530 and the TWL4030 (ok, I guess its the TPS65950
now) companion chip on the Beagleboard. Specifically, I'm trying to
figure out when the TPS65950's Vbus line (pin R8) actually starts
providing the +5V output that is available to USB peripherals. With
the ID input (pin R11) to the the TPS65950 tied to ground (the same
one that can be solder bridged to ground at the input of the miniUSB
port), if I soft reset my Beagleboard, it appears as though the Vbus
line goes to +5V almost immediately after the kernel is done
uncompressing.
So my question: does the TPS65950 automatically output +5V if its ID
input is tied to ground? Or, is there some additional configuration
that is executed by the OMAP3530 (I2C commands?) to instruct the
TPS65950 to output +5V on the Vbus line? I'm assuming its the latter,
and would appreciate any guidance as to what magic happens to make the
TPS65950 properly output +5V on Vbus.
Thanks much,
John