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©Copyright 2000-2007 SD Card Association
SDIO Simplified Specification Version 2.00
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6.14 Bus State Diagram
Figure 6-2 shows the Bus State Diagram for an SDIO card. It shows the bus states and their relations to SDIO
commands and Suspend/Resume.
Figure 6-2 State Diagram for Bus State Machine
Commands
accepted in “INI”
CMD5, CMD3
CMD15
Initialization
State
Power On
Standby
State
Command
State
(Dat Bus Free)
BS=0
Transfer
State
(Dat Bus Active)
BS=1
Inactive
State
CMD3
CMD52 Reset
CMD7 with
correct RCA
CMD7 with
incorrect RCA
CMD53 (to valid
function)
Function
Resume
Execution complete
Function Suspend
CMD52 Abort
CMD52 Reset
CMD15 or OCR
mismatch
CMD7 with correct
RCA
CMD53 to invalid
function
Commands
accepted in “CMD”
CMD7, CMD52,
CMD53, CMD15
Commands
accepted in “TRN”
CMD52
Commands
accepted in “STB”
CMD3, CMD7,
CMD15
CMD53 to invalid function can be:
y
I/O Disable or I/O Not Ready (IORDY=0)
y
I/O Function number error in response
y
I/O Function already Suspended