Texas Instruments TMS320DM644x manual Checking For a Data Transmit Empty Condition

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Peripheral Architecture

2.9.7.8Determining When Last Data has Been Written to Card (SanDisk SD cards)

Some SanDisk brand SD™ cards exhibit a behavior that requires a multiple-block write command to terminate with a STOP (CMD12) command before the data write sequence completes. To enable support of this function, the transfer done interrupt (TRNDNE) is provided. Set the ETRNDNE bit in MMCIM to enable the TRNDNE interrupt. This interrupt is issued when the last byte of data (as defined by MMCNBLK and MMCBLEN) is transferred from the FIFO to the output shift register. The CPU should respond to this interrupt by sending a STOP command to the card. This interrupt differs from DATDNE by timing. DATDNE does not occur until after the CRC and memory programming are complete.

2.9.7.9Checking For a Data Transmit Empty Condition

During transmission, a data value is passed from the MMC data transmit register (MMCDXR) to the data transmit shift register. The data is then passed from the shift register to the memory card one bit at a time. The DXEMP bit in MMCST1 indicates when the shift register is empty.

Typically, the DXEMP bit is not used to control data transfers; rather, it is checked during recovery from an error condition. There is no interrupt associated with the DXEMP bit.

2.9.7.10Checking for a Data Receive Full Condition

During reception, the data receive shift register accepts a data value one bit at a time. The entire value is then passed from the shift register to the MMC data receive register (MMCDRR). The DRFUL bit in MMCST1 indicates that when the shift register is full no new bits can be shifted in from the memory card.

The DRFUL bit is not typically used to control data transfers; rather, it is checked during recovery from an error condition. There is no interrupt associated with the DRFUL bit.

2.9.7.11Checking the Status of the SD_CLK Pin

Read the CLKSTP bit in MMCST1 to determine whether the memory clock has been stopped on the SD_CLK pin.

2.9.7.12Checking the Remaining Block Count During a Multiple-Block Transfer

During a transfer of multiple data blocks, the MMC number of blocks counter register (MMCNBLC) indicates how many blocks are remaining to be transferred. The MMCNBLC is a read-only register.

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Multimedia Card (MMC)/Secure Digital (SD) Card Controller

SPRUE30B –September 2006

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Contents Users Guide Submit Documentation Feedback Contents Appendix a List of Figures List of Tables Read This First Trademarks Purpose of the Peripheral FeaturesFunctional Block Diagram Supported Use Case Statement Industry Standards Compliance StatementMMC/SD Controller Interface Diagram MMC/SD Controller Clocking Diagram Clock Control1 MMC/SD Mode Write Sequence Signal DescriptionsMMC/SD Controller Pins Used in Each Mode Protocol DescriptionsPortion Sequence Description MMC/SD Mode Write Sequence2 MMC/SD Mode Read Sequence CRC MMC/SD Mode Read SequenceData Flow in the Input/Output Fifo RD CMDFifo Operation Diagram Data Flow in the Data Registers Mmcdrr and Mmcdxr 1st 2nd 3rd 4th Mmcdrr or Mmcdxr registers Support byten =1st 2nd 3rd 4th Support byten = 1111 1110 CPU Reads Fifo Operation During Card Read OperationEdma Reads Fifo Operation During Card Read Diagram CPU Writes Fifo Operation During Card Write OperationEdma Writes Fifo Operation During Card Write Diagram Reset Considerations InitializationInitialize the Time-Out Registers Mmctor and Mmctod Initializing the Clock Controller Registers MmcclkInitialize the Interrupt Mask Register Mmcim Initialize the Data Block Registers Mmcblen and MmcnblkMonitoring Activity in the MMC/SD Mode Determining Whether New Data is Available in MmcdrrChecking For a Data Transmit Empty Condition Interrupt Multiplexing Interrupt SupportInterrupt Events and Requests Description of MMC/SD Interrupt RequestsEmulation Considerations Power ManagementDMA Event Support MMC Card Identification Procedure Card Identification OperationProcedures for Common Operations SD Card Identification Procedure MMC/SD Mode Single-Block Write Operation Using CPU MMC/SD Mode Single-Block Write Operation MMC/SD Mode Single-Block Write Operation Using the Edma MMC/SD Mode Single-Block Read Operation Using the CPUMMC/SD Mode Single-Block Read Operation Using Edma MMC/SD Mode Single-Block Read OperationMMC/SD Mode Multiple-Block Write Operation Using CPU MMC/SD Multiple-Block Write Operation MMC/SD Mode Multiple-Block Write Operation Using Edma MMC/SD Mode Multiple-Block Read Operation Using CPUMMC/SD Mode Multiple-Block Read Operation Using Edma MMC/SD Mode Multiple-Block Read OperationOffset Acronym Register Description Bit Field Value Description MMC Control Register MmcctlMMC Control Register Mmcctl Field Descriptions Clken Clkrt MMC Memory Clock Control Register MmcclkMMC Memory Clock Control Register Mmcclk Field Descriptions ClkenBit Field MMC Status Register 0 MMCST0MMC Status Register 0 MMCST0 Field Descriptions Write-data CRC error Fifoful Fifoemp DAT3ST Drful Dxemp Clkstp Busy MMC Status Register 1 MMCST1MMC Status Register 1 MMCST1 Field Descriptions FifofulEtrndne Edated Edrrdy Edxrdy MMC Interrupt Mask Register MmcimMMC Interrupt Mask Register Mmcim Field Descriptions EtrndneTOR MMC Response Time-Out Register MmctorMMC Response Time-Out Register Mmctor Field Descriptions MMC Data Read Time-Out Register Mmctod MMC Data Read Time-Out Register Mmctod Field DescriptionsBlen MMC Block Length Register MmcblenMMC Block Length Register Mmcblen Field Descriptions MMC Number of Blocks Register Mmcnblk Field Descriptions MMC Number of Blocks Register MmcnblkMMC Number of Blocks Counter Register Mmcnblc NblkMMC Data Receive Register Mmcdrr Field Descriptions MMC Data Receive Register MmcdrrMMC Data Transmit Register Mmcdxr MMC Data Transmit Register Mmcdxr Field DescriptionsDmatrig MMC Command Register MmccmdMMC Command Register Mmccmd Field Descriptions Dclr Initck Wdatx Strmtp Dtrw Rspfmt Bsyexp PplenCRC7 Stream enableBit Position Command Register Description Argh MMC Argument Register MmcarghlMMC Argument Register Mmcarghl Field Descriptions ArglMMC Response Registers MMCRSP0-MMCRSP7 Bit Position of Response Register R1, R3, R4, R5, or R6 Response 48 BitsR2 Response 136 Bits MMCRSP4-0MMC Data Response Register Mmcdrsp MMC Command Index Register MmccidxMMC Command Index Register Mmccidx Field Descriptions MMC Data Response Register Mmcdrsp Field DescriptionsAccwd Fifolev Fifodir Fiforst MMC Fifo Control Register MmcfifoctlMMC Fifo Control Register Mmcfifoctl Field Descriptions AccwdTable A-1. Document Revision History Reference Additions/Modifications/DeletionsAppendix a Important Notice
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