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REF: BB_SRM_xM
BeagleBoard-xM System
Reference Manual
Revision C2
Page 18 of 163
please refer to
http://focus.ti.com/lit/er/sprz319a/sprz319a.pdf
resolved by ES1.1 that are anticipated to have any impact on the operation of the
BeagleBoard-xM.
2.5
–
xM Revision B vs.
–
xM Revision C
There were seven changes made to the BeagleBoard-xM Rev C version over the Rev B
design.
o
Resistor loading was changed to allow for the reading of the Rev C
revision by the SW. GPIO171=0, GPIO_172=1, and GPIO_173=0.
o
Replacement of the processor from ES1.1 to ES1.2. For a detailed
description of the issues present in the ES1.2 revision, please refer to
http://focus.ti.com/lit/er/sprz319a/sprz319a.pdf
resolved by ES1.2 that are anticipated to have any impact on the operation
of the BeagleBoard-xM. ES1.2 is the latest revision.
o
Fixed capacitor footprint in the PCB layout.
o
Replaced the microSD connector with a new part. The current part was
targeted for EOL and a new one was required. This required a PCB
footprint change.
o
Redesigned the overvoltage protection circuit. We were seeing issues with
a small number of boards being damaged on the TPS2054 USB power
FET, so a new design was implemented. Overall operation is the same as
the original version with te exception that it is now possible to power the
entire board over the USB OTG port. This includes the HUB. Care should
be taken not to add high current devices on the USB ports as that will
cause the host to shut down the USB port,
o
Changed the default power state of the USB HUB to OFF as an added
layer of protection to make sure the USB power rails are off on initial
power up. This will minimize the initial current drain on the board. SW
can turn on the HUB power as needed by setting the TPS65950
LEDA/VIBRA.P pin LO to turn it on.
o
Added the ability for the SW to detect when the board is powered from the
DC supply or the OTG supply. Status is read from GPIO.6 pin on the
TPS65950. If LO, then the board is powered from the DC jack. The HUB
will only work in the DC powered mode so this change allows the board to
know not to try and initialize the USB Host when under OTG power.
Содержание XM C2
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