Voltage Switches - Altera Cyclone V Device Handbook

cv_54011
2013.12.30
Discovering Removable MMC4.3 Boot Mode Support
For removable MMC4.3 cards, the software driver must perform the following steps:
1. Discover the card as described in Enumerated Card Stack.
2. Read the MMC card device's EXT_CSD registers and examine the following fields:
• BOOT_PARTITION_ENABLE
• BOOT_SIZE_MULT
• BOOT_INFO
Note:
3. If the host processor needs to perform a boot operation at the next power-up cycle, it can manipulate the
contents of the EXT_CSD registers in the MMC card device, by using a SWITCH_FUNC command.
4. After this step, the software driver must power down the card by writing to the pwren register.
5. From here on, use the same steps as in Alternative Boot Operation for eMMC Card Devices.
Note:
Related Information
• Enumerated Card Stack
Refer to this section for more information on discovering removable MMC cards.
• www.jedec.org
For more information, refer to "Access to Boot Partition" in JEDEC Standard No. JESD84-A43, available
on the JEDEC website.
• Alternative Boot Operation for eMMC Card Devices
Refer to this section for information about alternative boot operation steps.

Voltage Switches

This section describes the general steps to switch voltage level.
The SD/MMC cards support various operating voltages, for example 1.8V and 3.3V. If you have a card which
is at 1.8V and you eject it and replace it with another card, which is 3.3V, then voltage switching is required.
In order to have the right voltage level to power the card, separate devices on the board are required: voltage
translation transceiver and power regulator/supply. When the software is aware that voltage switching is
needed, it should control the power regulator to supply another voltage level to the card (i.e. switching
between 1.8V and 3.3V).
However, for the HPS (or Altera device), the I/O pins are connected to the SD/MMC card running at 3.3V.
If your card runs at 1.8V, the voltage-translation transceiver is needed for voltage translation between the
HPS and the SD/MMC card.
SD/MMC Controller
Send Feedback
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For more information, refer to "Access to Boot Partition" in JEDEC Standard No. JESD84-A43,
available on the JEDEC website.
Ignore the EBE if it is generated during an abort scenario.
If a boot acknowledge error occurs, the boot acknowledge received interrupt times out.
In internal DMA controller mode, the application needs to depend on the descriptor close interrupt
instead of the data done interrupt.
on page 11-31
Discovering Removable MMC4.3 Boot Mode Support
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on page 11-67
11-71
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Altera Corporation