Product manual

4-18 SanDisk miniSD Card Product Manual, Rev. 1.1 © 2003 SANDISK CORPORATION
4.8. Commands
The following sections provide valuable information on commands.
4.8.1. Command Types
There are four kinds of commands defined to control the miniSD Card:
• Broadcast Commands (bc), no response—The broadcast feature is applicable only if all the CMD lines
are connected together in the host. If they are separated then each card will accept it separately on his
turn.
• Broadcast Commands with Response (bcr)—response from all cards simultaneously. Since there is no
Open Drain mode in miniSD Card, this type of command is used only if all the CMD lines are
separated. The command will be accepted and responded to by every card separately.
• Addressed (point-to-point) Commands (ac)—no data transfer on DAT.
• Addressed (point-to-point) Data Transfer Commands (adtc)—data transfer on DAT.
All commands and responses are sent over the CMD line of the miniSD Card. The command transmission always
starts with the left bit of the bit string corresponding to the command code word.
4.8.2. Command Format
(Command length 48 bits, 1.92 µs @ 25 MHz)
0 1 bit 5...bit 0 bit 31...bit 0 bit 6...bit 0 1
start bit host command argument CRC7
1
end bit
Commands and arguments are listed in Table 5-3 through Table 5-10.
7-bit CRC Calculation: G(x) = x
7 +
x
3 +
1
M(x) = (start bit)∗x
39
+ (host bit)∗x
38
+...+ (last bit before CRC)∗x
0
CRC[6...0] = Remainder[(M(x)∗x
7
)/G(x)]
4.8.3. Command Classes
The command set of the miniSD Card is divided into several classes (refer to Figure 4-2). Each class supports a set
of miniSD Card functions.
The supported Card Command Classes (CCC) are coded as a parameter in the card specific data (CSD) register of
each card, providing the host with information on how to access the card.
1) 7-bit Cyclic Redundancy Check.