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SDIO Simplified Specification Version 2.00
Field | Type |
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| Description | |
FSx | R/W | Select Function bits 3:0 These four bits are used to select a function number | |||
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| the memory of a combo card (8) for Suspend/Resume. There are 2 means to write | |||
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| the value of FSx. First, an I/O writes to the register in the CCCR and second, a new | |||
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| I/O command causes the FSx to be set to the function number in that command. The | |||
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| value of FSx shall remain until overwritten. If a function or memory is currently | |||
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| suspended, the writing of it’s number to FSx shall | |||
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| operation When reading FSx, the value returned shall be the number of the currently | |||
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| addressed function. Note that when reading FSx, if the Bus Status is 0 (BS=0), the | |||
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| FSx value is undefined. The FSx bits are coded as follows: | |||
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| FSx | Current Transaction |
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| 0000 | Transaction of function 0 (CIA) | |
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| Transaction to functions | |||
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| 1000 | Transaction of memory in combo card | ||
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| Not defined, reserved for future use | |||
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| If SBS=0 these bits shall be R/O. | |||
DF | R/O | Resume Data Flag: A data transaction is resumed by writing its number to FSx. Once | |||
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| the transaction is resumed, the DF indicates if more data will be transferred. If DF is | |||
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| cleared to 0, then no additional data will be transferred after the function or memory is | |||
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| resumed. If DF is set to 1, then there is more data to transfer that will begin after the | |||
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| function or memory in resumed. The DF flag can be used to control the interrupt cycle | |||
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| in | |||
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| this case, the interrupt cycle should be disabled. If DF=0, the function or memory was | |||
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| suspended at end of data transfer (during busy). In this case, no data transfer shall | |||
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| begin after resume so the host can detect a start interrupt cycle after restore. When | |||
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| resuming, if the suspended function cannot continue data transfer the card shall | |||
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| return DF=0 to abort the transfer. | |||
EXx | R/O | Execution Flag bits 7:0 These bits are used by the host to determine the current | |||
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| execution status of all functions | |||
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| function or memory that is currently executing a command. The EXx bits tell the host | |||
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| that a function or memory is currently executing a command so no additional | |||
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| command should be issued to that function/memory. These bits are only defined if | |||
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| SBS=1. This bit is set if the function is active (either currently executing or | |||
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| suspended). If SBS=0 these bits shall be read as zero. | |||
RFx | R/O | Ready Flag bits 7:0 These bits tell the host the read or write busy status for functions | |||
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| ||||
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| bit cleared to 0 indicates the function/memory is busy and not ready to accept more | |||
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| data. If the RFx bit is set to 1, then the function/memory can accept write data. If a | |||
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| function/memory is executing a read command, if the RFx bit is cleared to 0, it | |||
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| indicates that read data is NOT available. If the bit is set to 1, it indicates that read | |||
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| data is ready to be transferred. These bits are only defined if SBS=1. Setting a bit to 1 | |||
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| indicates the function is ready to accept the resume command. There are two | |||
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| conditions where the function will set the bit to 1. One is when the function (executing | |||
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| or suspended) is ready to continue data transfer. The other is when the suspended | |||
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| function cannot continue data transfer. If SBS=0 these bits shall be read as zero. | |||
FN0 Block | R/W | This | |||
Size |
| this card does not support I/O block operations (SMB=0), then this register becomes | |||
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| ||||
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| and the minimum is 1. At | |||
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| value of 0x0000. The host is responsible for setting the appropriate value for the | |||
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| block size supported by function 0. This pointer is stored in | |||
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| first). |
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