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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 262
UG585 (v1.11) September 27, 2016
Chapter 9: DMA Controller
The memory map for the DMA controller is shown in Chapter 4, System Addresses.
For more information on the AXI Interfaces, refer to . Examples of memory-to-memory transfer are
provided in section 9.4.2 Memory-to-Memory Transfers.
9.2.6 PL Peripheral AXI Transactions
The majority of PL peripherals allow transferring data through FIFOs. These FIFOs must be managed
to avoid overflow and underflow situations. For this reason, four specific peripheral request
interfaces are available to connect the DMAC to DMA-capable peripherals in the PL. Each one of
these interfaces can be assigned to any DMA channel.
The DMAC is configured to accept up to four active requests for each PL peripheral interface. An
active request is where the DMAC has not started the requested AXI data transaction. The DMAC has
a request FIFO for each PL peripheral interface, which it uses to capture the requests from a PL
peripheral. When a request FIFO is full, the DMAC sets the corresponding DMA{3:0}_DRREADY Low to
signal that the DMAC cannot accept any requests sent from the PL peripheral.
Note: There are no peripheral request interfaces directed to the I/O peripherals (IOP) in the PS.
Processor intervention is needed to avoid underflow or overflow of the FIFOs in the targeted PS
peripheral. This section discusses the AXI transactions to/from PL peripherals.
There are two different way to handle the quantity of data flowing between the DMAC and the PL
peripheral:
PL Peripheral length management: The PL peripheral controls the quantity of data that is
contained in a DMA cycle.
DMAC length management: The DMAC is controlling the quantity of data in a DMA
cycle.
Programming Examples
Refer to section 9.4.3 PL Peripheral DMA Transfer Length Management.
9.2.7 PL Peripheral Request Interface
Figure 9-4 shows that the PL peripheral request interface consists of a PL peripheral request bus and
a DMAC acknowledge bus that use the prefixes:
DR PL Peripheral request bus
DA DMAC acknowledge bus