Memory Card Specification Sheet

©Copyright 2000-2007 SD Card Association
SDIO Simplified Specification Version 2.00
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3.2 The IO_SEND_OP_COND Command (CMD5)
Figure 3-4 shows the format of the IO_SEND_OP_COND command (CMD5). The function of CMD5 for SDIO
cards is similar to the operation of ACMD41 for SD memory cards. It is used to inquire about the voltage range
needed by the I/O card. The normal response to CMD5 is R4 in either SD or SPI format. The R4 response in SD
mode is shown in Figure 3-5 and the SPI version is shown in Figure 3-6.
S
D
Command Index
000101b
Stuff
Bits
I/O OCR CRC7 E
1 1 6 8 24 7 1
Figure 3-4 IO_SEND_OP_COND Command (CMD5)
The IO_SEND_OP_COND Command contains the following fields:
S(tart bit): Start bit. Always 0
D(irection): Direction. Always1 indicates transfer from host to card.
Command Index: Identifies the CMD5 command with a value of 000101b
Stuff Bits: Not used, shall be set to 0.
I/O OCR:
Operation Conditions Register. The supported minimum and maximum values
for VDD. The layout of the OCR is shown in Table 3-1. See section 4.10.1 for
additional information.
CRC7: 7 bits of CRC data
E(nd bit): End bit, always 1
I/O OCR bit
position
VDD Voltage Window
(in Volts)
0-3 Reserved
4 Reserved
5 Reserved
6 Reserved
7 Reserved
8 2.0-2.1
9 2.1-2.2
10 2.2-2.3
11 2.3-2.4
12 2.4-2.5
13 2.5-2.6
14 2.6-2.7
15 2.7-2.8
16 2.8-2.9
17 2.9-3.0
18 3.0-3.1
19 3.1-3.2
20 3.2-3.3
21 3.3-3.4
22 3.4-3.5
23 3.5-3.6
Table 3-1 OCR Values for CMD5
The SDIO Version 2.00 cards shall support the operational voltage range 2.7-3.6V and are not necessary to
support the voltage range 2.0-2.7V for basic communication. The hosts, which support SDIO Version 2.00, shall
not use voltage range 2.0-2.7V for basic communication.