High Performance DMA Controller
UG0331 User Guide Revision 15.0
241
8.2.2
Details of Operation
After initialization, the HPDMA is ready to function in one of the two following data transfer modes:
•
AHB bus matrix to MSS DDR bridge
•
MSS DDR bridge to AHB bus matrix
For initiation of the above data transfer modes, a descriptor valid bit has to be set (that is, bit 16 of the
Descriptor control register is asserted). If all the four descriptors are configured and set to valid, the
descriptor transfer begins and executes in a round robin fashion. If any of the descriptor is paused by
setting the bit 19 of Descriptor control register, the HPDMA stops the data transfer. HPDMA resumes the
operation once the pause bit is reset. The pending transfers of the source and destination can be read
from the Descriptor pending transfer register (HPDMADXPTR, where X is 0 to 3).
HPDMA can service the next descriptor only after the pending transfer of the current descriptor is
complete. The data transfer completion interrupt is monitored using bit 20 of the Descriptor control
register and bit 1 of the Descriptor status register. Refer to the
HPDMA Register Bit Definitions,
for more information on HPDMA registers.
8.3
How to Use HPDMA
This section describes how to use the HPDMA in an application.
8.3.1
Design Flow
The following steps describe how to enable HPDMA in the application:
Содержание SmartFusion2 MSS
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