beaglebone-black - Flipbook - Page 52
BeagleBone Black
The following sections describe the design and device that is used on the board to implement this interface.
6.2.11
eMMC Device
The device used is one of two di昀昀erent devices:
• Micron MTFC4GLDEA 0M WT
• Kingston KE4CN2H5A-A58
The package is a 153 ball WFBGA device on both devices.
6.2.12
eMMC Circuit Design
昀椀gure-34 is the design of the eMMC circuitry. The eMMC device is connected to the MMC1 port on the processor.
MMC0 is still used for the microSD card as is currently done on the original BeagleBone. The size of the eMMC
supplied is now 4GB.
The device runs at 3.3V both internally and the external I/O rails. The VCCI is an internal voltage rail to the
device. The manufacturer recommends that a 1uF capacitor be attached to this rail, but a 2.2uF was chosen
to provide a little margin.
Pullup resistors are used to increase the rise time on the signals to compensate for any capacitance on the
board.
Fig. 6.15: eMMC Memory Design
The pins used by the eMMC1 in the boot mode are listed below in Table 6.
Fig. 6.16: eMMC Boot Pins
For eMMC devices the ROM will only support raw mode. The ROM Code reads out raw sectors from image or
the booting 昀椀le within the 昀椀le system and boots from it. In raw mode the booting image can be located at
one of the four consecutive locations in the main area: o昀昀set 0x0 / 0x20000 (128 KB) / 0x40000 (256 KB) /
0x60000 (384 KB). For this reason, a booting image shall not exceed 128KB in size. However it is possible to
昀氀ash a device with an image greater than 128KB starting at one of the aforementioned locations. Therefore
6.2. Sitara AM3358BZCZ100 Processor
47
