beaglebone-black - Flipbook - Page 57
BeagleBone Black
If you have a microSD card from which you need to boot from, hold the boot button down. On boot, the
processor will look for the SPIO0 port 昀椀rst, then microSD on the MMC0 port, followed by USB0 and UART0. In
the event there is no microSD card and the eMMC is empty, USB0 or UART0 could be used as the board source.
6.4 10/100 Ethernet
The BeagleBone Black is equipped with a 10/100 Ethernet interface. It uses the same PHY as is used on the
original BeagleBone. The design is described in the following sections.
6.4.1 Ethernet Processor Interface
Fig. 6.22: Ethernet Processor Interface
This is the same interface as is used on the BeagleBone. No changes were made in this design for the board.
6.4.2 Ethernet Connector Interface
The o昀昀 board side of the PHY connections are shown in Figure 41 below.
This is the same interface as is used on the BeagleBone. No changes were made in this design for the board.
6.4.3 Ethernet PHY Power, Reset, and Clocks
VDD_3V3B Rail
The VDD_3V3B rail is the main power rail for the LAN8710A. It originates at the VD_3V3B regulator and is the
primary rail that supports all of the peripherals on the board. This rail also supplies the VDDIO rails which set
the voltage levels for all of the I/O signals between the processor and the**LAN8710A**.
VDD_PHYA Rail
A 昀椀ltered version of VDD_3V3B rail is connected to the VDD rails of the LAN8710 and the termination resistors
on the Ethernet signals. It is labeled as VDD_PHYA. The 昀椀ltering inductor helps block transients that may be
seen on the VDD_3V3B rail.
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Chapter 6. Detailed Hardware Design
