REF: BBONEBLK_SRM
BeagleBone Black System
Reference Manual
Rev A5.2
Page 55 of 108
flash a device with an image greater than 128KB starting at one of the aforementioned
locations. Therefore the ROM Code does not check the image size. The only drawback is
that the image will cross the subsequent image boundary. The raw mode is detected by
reading sectors #0, #256, #512, #768. The content of these sectors is then verified for
presence of a TOC structure. In the case of a
GP Device
, a Configuration Header (CH)
must
be located in the first sector followed by a
GP header
. The CH might be void (only
containing a CHSETTINGS item for which the Valid field is zero).
The ROM only supports the 4-bit mode. After the initial boot, the switch can be made to
8-bit mode for increasing the overall performance of the eMMC interface.
6.5
Micro Secure Digital
The uSD connector on the board will support a uSD card that can be used for booting or
file storage on the BeagleBone Black.
6.5.1
uSD Design
Figure 33
below is the design of the uSD interface on the board.
U5A
AM3358_ZCZ
MMC0_CLK
G17
MMC0_CMD
G18
MMC0_DAT0
G16
MMC0_DAT1
G15
MMC0_DAT2
F18
MMC0_DAT3
F17
MMC0_SDCD
C15
DGND
SD_CD
DGND
R
15
0
10
K,
1%
R
15
3
10
K,
1%
R
15
1
10
K,
1%
R157
10K,1%
R
15
2
10
K,
1%
R
15
4
10
K,
1%
R
15
5
10
K,
1%
VDD_3V3B
VDD_3V3B
DGND
C153
10uF,10V
microSD
P7
MOLEX 502570-001
DAT2
1
CD/DAT3
2
CMD
3
VDD
4
CLOCK
5
VSS
6
DAT0
7
DAT1
8
GND
9
GND1
10
CD
11
GND2
12
GND3
13
GND4
14
C154
0.1uf ,6.3V
Figure 33.
uSD Design
The signals
MMC0-3
are the data lines for the transfer of data between the processor and
the uSD connector.
The
MMC0_CLK
signal clocks the data in and out of the uSD card.
The
MMCO_CMD
signal indicates that a command versus data is being sent.
There is no separate card detect pin in the uSD specification. It uses
MMCO_DAT3
for
that function. However, most uSD connectors still supply a CD function on the
Содержание BBONEBLK_SRM
Страница 103: ...REF BBONEBLK_SRM BeagleBone Black System Reference Manual Rev A5 2 Page 103 of 108 Figure 65 Component Side Silkscreen...
Страница 104: ...REF BBONEBLK_SRM BeagleBone Black System Reference Manual Rev A5 2 Page 104 of 108 Figure 66 Component Side Silkscreen...
Страница 105: ...REF BBONEBLK_SRM BeagleBone Black System Reference Manual Rev A5 2 Page 105 of 108 10 0 Pictures Figure 67 Top Side...
Страница 106: ...REF BBONEBLK_SRM BeagleBone Black System Reference Manual Rev A5 2 Page 106 of 108 Figure 68 Bottom Side...
