Altera cyclone V Technical Reference page 3513

A-14
SD/MMC Flash Devices
The SD/MMC controller supports two booting modes:
• MBR (partition) mode
• The boot image is read from a custom partition (0xA2)
• The first image is located at the beginning of the partition, at offset 0x0
• Start address = partition start address
• Raw mode
• If the MBR signature is not found, SD/MMC driver assumes it is in raw mode
• The boot image data is read directly from sectors in the user area and is located at the first sector of
the SD/MMC
• The first image is located at the start of the memory card, at offset 0x0
• Start address = 0x0
The MBR contains the partition table, which is always located in the first sector (LBA0) with a memory
size of 512 bytes. The MBR consists of executable code, four partition entries, and the MBR signature. A
MBR can be created by specific tools like the FDISK program.
Table A-9: MBR Structure
Offset
0x000
0x1BE
0x1CE
0x1DE
0x1EE
0x1FE
The standard MBR structure contains a partition with four 16-byte entries. Thus, memory cards using this
standard table cannot have more than four primary partitions or up to three primary partitions and one
extended partition.
Each partition type is defined by the partition entry. The boot images are stored in a primary partition
with custom partition type (0xA2). The SD/MMC flash driver does not support a file system, so the boot
images are located in partition A2 at fixed locations.
Altera Corporation
Size (In Bytes)
446
16
16
16
16
2
Description
Code area
Partition entry for partition 1
Partition entry for partition 2
Partition entry for partition 3
Partition entry for partition 4
MBR signature: 0xAA55
Booting and Configuration
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2016.10.28