beaglebone-black - Flipbook - Page 46
BeagleBone Black
The 昀椀rst is the I2C0 bus. This allows the processor to turn on and o昀昀 rails and to set the voltage levels of each
regulator to supports such things as voltage scaling.
The second is the interrupt signal. This allows the TPS65217C to alert the processor when there is an event,
such as when the power button is pressed. The interrupt is an open drain output which makes it easy to
interface to 3.3V of the processor.
6.1.13
Low Power Mode Support
This section covers three general power down modes that are available. These modes are only described from
a Hardware perspective as it relates to the HW design.
RTC Only
In this mode all rails are turned o昀昀 except the VDD_RTC. The processor will need to turn o昀昀 all the rails to
enter this mode. The VDD_RTC staying on will keep the RTC active and provide for the wakeup interfaces to
be active to respond to a wake up event.
RTC Plus DDR
In this mode all rails are turned o昀昀 except the VDD_RTC and the VDDS_DDR, which powers the DDR3L memory.
The processor will need to turn o昀昀 all the rails to enter this mode. The VDD_RTC staying on will keep the RTC
active and provide for the wakeup interfaces to be active to respond to a wake up event.
The VDDS_DDR rail to the DDR3L is provided by the 1.5V rail of the TPS65217C and with VDDS_DDR active,
the DDR3L can be placed in a self refresh mode by the processor prior to power down which allows the memory
data to be saved.
Currently, this feature is not included in the standard software release. The plan is to include it in future
releases.
Voltage Scaling
For a mode where the lowest power is possible without going to sleep, this mode allows the voltage on the ARM
processor to be lowered along with slowing the processor frequency down. The I2C0 bus is used to control the
voltage scaling function in the TPS65217C.
6.2 Sitara AM3358BZCZ100 Processor
The board is designed to use the Sitara AM3358BZCZ100 processor in the 15 x 15 package. Earlier revisions
of the board used the XM3359AZCZ100 processor.
6.2.1 Description
Figure below shows is a high level block diagram of the processor. For more information on the processor, go
to http://www.ti.com/product/am3358
6.2.2 High Level Features
Table 6.3: Processor Features
Operating Systems
Linux,
Android,
Windows
Embedded
CE,QNX,ThreadX
MMC/SD
3
Standby Power
ARM CPU
7 mW
1 ARM Cortex-A8
CAN
UART (SCI)
2
6
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6.2. Sitara AM3358BZCZ100 Processor
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