RM0082
BS_DMA controller
Doc ID 018672 Rev 1
335/844
Table 277.
DMAC signal interface
19.4
Main functions description
19.4.1 AHB
slave
interface
The
AHB slave interface
block allows to connect the DMAC to the AMBA AHB bus.
In particular, the AHB slave interface properly decodes read and write command on AHB
bus providing access to DMAC memory-mapped registers for configuration purposes.
It is worth noticing that the AHB slave and the two AHB masters use the same clock, HCLK,
that is they are all synchronous.
19.4.2
AHB master interfaces
The DMAC contains two full independent AHB masters for data transfer. This feature allows,
for example, the DMAC to transfer data directly from the memory connected to AHB port #1
to any AHB peripheral connected to AHB port #2. Besides, it enables transactions between
the DMAC and any APB peripheral to occur independently of transactions on AHB bus 1.
Each AHB master is capable of dealing with all types of AHB transactions, including:
●
Split, retry and error responses from AHB slaves. If a peripheral performs a split or
retry, the DMAC stalls and waits until the transaction can complete.
●
Locked transfers for source and destination of each stream.
●
Setting of protection bits for transfers on each stream.
The two AHB masters are connected to buses of the same width (the default is a 32 bit bus).
However, source and destination transfers can be with different widths, and can be the same
Group
Signal name
Direction
Size
(bit)
Description
DMA request
DMACBREQ
Input
16
DMA burst transfer request.
DMACLBREQ
Input
16
DMA last burst transfer request.
DMACSREQ
Input
16
DMA single transfer request.
DMACLSREQ
Input
16
DMA last single transfer request
DMA response
DMACCLR
Output
16
DMA request clear.
DMACTC
Output
16
DMA terminal count (transaction
complete).
Interrupt
request
DMACINTERR
Output
1
DMA error interrupt request.
DMACINTTC
Output
1
DMA terminal count interrupt request.
DMACINTR
Output
1
DMA interrupt request. This signal
combines the
DMACINTERR
and
DMACINTTC
requests.
AHB Master #1 -
Input/Output -
See AMBA specification.
AHB Master #2 -
Input/Output -
See AMBA specification.
AHB Slave
-
Input/Output -
See AMBA specification.