Datasheet
884
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
register, no error recovery action is required. The ATA command itself failed implying that the device could not complete
the action requested, however, there was no communication or protocol failure. After the device signals an error by
setting the ERR bit to one in the ATA Status register, the host may attempt to retry the command.
38.11 HSMCI Boot Operation Mode
In boot operation mode, the processor can read boot data from the slave (MMC device) by keeping the CMD line low
after power-on before issuing CMD1. The data can be read from either the boot area or user area, depending on register
setting. As it is not possible to boot directly on SD-CARD, a preliminary boot code must be stored in internal Flash.
38.11.1 Boot Procedure, Processor Mode
1. Configure the HSMCI data bus width programming SDCBUS Field in the HSMCI_SDCR. The
BOOT_BUS_WIDTH field located in the device Extended CSD register must be set accordingly.
2. Set the byte count to 512 bytes and the block count to the desired number of blocks, writing BLKLEN and BCNT
fields of the HSMCI_BLKR.
3. Issue the Boot Operation Request command by writing to the HSMCI_CMDR with SPCMD field set to BOOTREQ,
TRDIR set to READ and TRCMD set to “start data transfer”.
4. The BOOT_ACK field located in the HSMCI_CMDR must be set to one, if the BOOT_ACK field of the MMC device
located in the Extended CSD register is set to one.
5. Host processor can copy boot data sequentially as soon as the RXRDY flag is asserted.
6. When Data transfer is completed, host processor shall terminate the boot stream by writing the HSMCI_CMDR
with SPCMD field set to BOOTEND.
38.12 HSMCI Transfer Done Timings
38.12.1 Definition
The XFRDONE flag in the HSMCI_SR indicates exactly when the read or write sequence is finished.
38.12.2 Read Access
During a read access, the XFRDONE flag behaves as shown in Figure 38-11.
Figure 38-11. XFRDONE During a Read Access
CMD line
HSMCI read CMD
Card response
CMDRDY flag
Data
1st Block
Last Block
Not busy flag
XFRDONE flag
The CMDRDY flag is released 8 tbit after the end of the card response.