Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK データシート

 958

SAM9M10 [DATASHEET]

6355F–ATARM–12-Mar-13

• There must not be any write operation to Channel registers in an active channel after the channel enable is 

made HIGH. If any channel parameters must be reprogrammed, this can only be done after disabling the DMAC 
channel.

• When destination peripheral is defined as the flow controller, source single transfer request are not serviced 

until Destination Peripheral has asserted its Last Transfer Flag.

• When Source Peripheral is flow controller, destination single transfer request are not serviced until Source 

Peripheral has asserted its Last Transfer Flag.

• When destination peripheral is defined as the flow controller, if the destination width is smaller than the source 

width, then a data loss may occur, and the loss is equal to Source Single Transfer size in bytes- destination 
Single Transfer size in bytes.

• When a Memory to Peripheral transfer occurs if the destination peripheral is flow controller, then a prefetch 

operation is performed. It means that data are extracted from memory before any request from the peripheral is 
generated.

• You must program the DMAC_SADDRx and DMAC_DADDRx channel registers with a byte, half-word and word 

aligned address depending on the source width and destination width.

• After the software disables a channel by writing into the channel disable register, it must re-enable the channel 

only after it has polled a 0 in the corresponding channel enable status register. This is because the current AHB 
Burst must terminate properly.

• If you program the BTSIZE field in the DMAC_CTRLA, as zero, and the DMAC is defined as the flow controller, 

then the channel is automatically disabled.

• When hardware handshaking interface protocol is fully implemented, a peripheral is expected to deassert any 

sreq or breq signals on receiving the ack signal irrespective of the request the ack was asserted in response to.

• Multiple Transfers involving the same peripheral must not be programmed and enabled on different channel, 

unless this peripheral integrates several hardware handshaking interface.

• When a Peripheral is flow controller, the targeted DMAC Channel must be enabled before the Peripheral. If you 

do not ensure this the DMAC Channel might miss a Last Transfer Flag, if the First DMAC request is also the last 
transfer.

• When AUTO Field is set to TRUE, then the BTSIZE Field is automatically reloaded from its previous value. 

BTSIZE must be initialized to a non zero value if the first transfer is initiated with AUTO field set to TRUE even if 
LLI mode is enabled because the LLI fetch operation will not update this field.