Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

571

SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

The following flowchart (

) shows how to read a single block with or without use of DMAC facilities. In this

example, a polling method is used to wait for the end of read. Similarly, the user can configure the Interrupt Enable
Register (HSMCI_IER) to trigger an interrupt at the end of read.

Notes: 1. It is assumed that this command has been correctly sent (see 

).

Read status register HSMCI_SR

Send  SELECT/DESELECT_CARD

command

(1)

  to select the card

Send SET_BLOCKLEN command

(1)

 

Read with DMAC

Number of words to read = 0 ?

Poll the bit

RXRDY = 0?

Read data = HSMCI_RDR

Number of words to read = 

Number of words to read  -1

Send READ_SINGLE_BLOCK

command

(1)

Yes

Set the DMAEN bit
HSMCI_DMA |= DMAEN
Set the block length (in bytes)
HSMCI_BLKR |= (BlockLength << 16)

Configure the DMA channel X
DMAC_SADDRx = Data Address
DMAC_BTSIZE = BlockLength/4
DMACHEN[X] = TRUE

Send READ_SINGLE_BLOCK

command

(1)

Read status register HSMCI_SR

Poll the bit

XFRDONE = 0?

Yes

RETURN

RETURN

Yes

No

No

No

Yes

No

Number of words to read = BlockLength/4

Reset the DMAEN bit
HSMCI_DMA &= ~DMAEN
Set the block length (in bytes)
HSMCI_BLKR  l= (BlockLength<<16)
Set the block count (if neccessary)
HSMCI_BLKR l= (BlockCount<<0)