Altera Cyclone V Device Handbook page 744

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Booting Removable MMC4.3, MMC4.4 and MMC4.41 Cards
Booting Removable MMC4.3, MMC4.4 and MMC4.41 Cards
For removable MMC4.3, MMC4.4 and MMC4.41 cards, the software driver must perform the following
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steps:
1. Discover the card as described in Enumerated Card Stack.
2. Read the EXT_CSD register of the card and examine the following fields:
• BOOT_PARTITION_ENABLE
• BOOT_SIZE_MULT
• BOOT_INFO
3. If necessary, the software can manipulate the boot information in the card.
Note: For more information, refer to "Access to Boot Partition" in the following specifications available
on the JEDEC website:
• JEDEC Standard No. 84-A441
• JEDEC Standard No. 84-A44
• JEDEC Standard No. JESD84-A43
4. If the host processor needs to perform a boot operation at the next power-up cycle, it can manipulate the
EXT_CSD register contents by using a SWITCH_FUNC command.
5. After this step, the software driver must power down the card by writing to the pwren register.
6. From here on, use the same steps as in Alternative Boot Operation for eMMC Card Devices.
Related Information
• Enumerated Card Stack
Refer to this section for more information on discovering removable MMC cards.
• www.jedec.org
• Alternative Boot Operation for eMMC Card Devices
Refer to this section for information about alternative boot operation steps.
Alternative Boot Operation
The alternative boot operation differs from the previous boot operation in that software uses the SD/SDIO
GO_IDLE_STATE command to boot the card, rather than holding down the CMD line of the card. The
alternative boot operation can be performed only if bit 0 in the BOOT_INFO register is set to 1. BOOT_INFO
is located at offset 228 in the EXT_CSD registers.
For detailed information about alternative boot operation, refer to the following specifications available on
the JEDEC website:
• JEDEC Standard No. 84-A441
• JEDEC Standard No. 84-A44
• JEDEC Standard No. JESD84-A43
Related Information
www.jedec.org
For more information about alternative boot operation, refer to the following JEDEC Standards available
on the JEDEC website: No. 84-A441, No. 84-A44, and No. JESD84-A43.
Altera Corporation
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on page 11-31
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on page 11-67
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2013.12.30
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SD/MMC Controller
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