beaglebone-black - Flipbook - Page 31
BeagleBone Black
5.2 Processor
The revision B and later boards have moved to the Sitara AM3358BZCZ100 device.
5.3 Memory
Described in the following sections are the three memory devices found on the board.
5.3.1 512MB DDR3L
A single 256Mb x16 DDR3L 4Gb (512MB) memory device is used. The memory used is one of two devices:
• MT41K256M16HA-125 from Micron
• D2516EC4BXGGB from Kingston
It will operate at a clock frequency of 400MHz yielding an e昀昀ective rate of 800MHZ on the DDR3L bus allowing
for 1.6GB/S of DDR3L memory bandwidth.
5.3.2 4KB EEPROM
A single 4KB EEPROM is provided on I2C0 that holds the board information. This information includes board
name, serial number, and revision information. This is the not the same as the one used on the original
BeagleBone. The device was changed for cost reduction reasons. It has a test point to allow the device to be
programmed and otherwise to provide write protection when not grounded.
5.3.3 4GB Embedded MMC
A single 4GB embedded MMC (eMMC) device is on the board. The device connects to the MMC1 port of the
processor, allowing for 8bit wide access. Default boot mode for the board will be MMC1 with an option to
change it to MMC0, the SD card slot, for booting from the SD card as a result of removing and reapplying the
power to the board. Simply pressing the reset button will not change the boot mode. MMC0 cannot be used
in 8Bit mode because the lower data pins are located on the pins used by the Ethernet port. This does not
interfere with SD card operation but it does make it unsuitable for use as an eMMC port if the 8 bit feature is
needed.
5.3.4 MicroSD Connector
The board is equipped with a single microSD connector to act as the secondary boot source for the board and,
if selected as such, can be the primary boot source. The connector will support larger capacity microSD cards.
The microSD card is not provided with the board. Booting from MMC0 will be used to 昀氀ash the eMMC in the
production environment or can be used by the user to update the SW as needed.
5.3.5 Boot Modes
As mentioned earlier, there are four boot modes:
• eMMC Boot: This is the default boot mode and will allow for the fastest boot time and will enable the
board to boot out of the box using the pre-昀氀ashed OS image without having to purchase an microSD card
or an microSD card writer.
• SD Boot: This mode will boot from the microSD slot. This mode can be used to override what is on the
eMMC device and can be used to program the eMMC when used in the manufacturing process or for 昀椀eld
updates.
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Chapter 5. BeagleBone Black High Level Speci昀椀cation
