Altera Cyclone V Device Handbook page 710

11-32
Identifying the Connected Card Type
a. Send an SD/SDIO IO_SEND_OP_COND (CMD5) command with argument 0 to the card.
b. Read resp0 on the controller. The response to the IO_SEND_OP_COND command gives the voltage
that the card supports.
c. Send the IO_SEND_OP_COND command, with the desired voltage window in the arguments. This
command sets the voltage window and makes the card exit the initialization state.
d. Check bit 27 in resp0:
• If bit 27 is 0, the SDIO card is IO ONLY. In this case, proceed to
• If bit 27 is 1, the card type is SDIO COMBO. Continue with the following steps.
3. Only continue with this step if the SDIO card type is COMBO or there is no response received from the
previous IO_SEND_OP_COND command. Otherwise, skip to
a. Send the SD/SDIO SEND_IF_COND (CMD8) command with the following arguments:
• Bit[31:12] = 0x0 (reserved bits)
• Bit[11:8] = 0x1 (supply voltage value)
• Bit[7:0] = 0xAA (preferred check pattern by SD memory cards compliant with SDIO Simplified
Specification Version 2.00 and later.)
Refer to SDIO Simplified Specification Version 2.00 as described on the SD Association website.
b. If a response is received to the previous SEND_IF_COND command, the card supports SD High-
Capacity, compliant with SD Specifications, Part 1, Physical Layer Simplified Specification Version
2.00.
If no response is received, proceed to
c. Send the SD_SEND_OP_COND (ACMD41) command with the following arguments:
• Bit[31] = 0x0 (reserved bits)
• Bit[30] = 0x1 (high capacity status)
• Bit[29:25] = 0x0 (reserved bits)
• Bit[24] = 0x1 (S18R --supports voltage switching for 1.8V)
• Bit[23:0] = supported voltage range
d. If a response is received to the previous SD_SEND_OP_COND command, the card type is SDHC.
Otherwise, the card is MMC or CE-ATA. In either case, skip the following steps and proceed to
5.
e. If a response is not received to the initial SEND_IF_COND command, the card does not support High
Capacity SD2.0. Next, issue the GO_IDLE_STATE command followed by the SD_SEND_OP_COND
command with the following arguments:
• Bit[31] = 0x0 (reserved bits)
• Bit[30] = 0x0 (high capacity status)
• Bit[29:24] = 0x0 (reserved bits)
• Bit[23:0] = supported voltage range
f. If a response is received to the previous SD_SEND_OP_COND command, the card is SD type.
Otherwise, the card is MMC or CE-ATA.
Note: You must issue the SEND_IF_COND command prior to the first SD_SEND_OP_COND
command, to initialize the High Capacity SD memory card. The card returns busy as a response
to the SD_SEND_OP_COND command when any of the following conditions are true:
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SD/MMC Controller
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2013.12.30
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