Visible to Intel only — GUID: iga1401397706978
Ixiasoft
Visible to Intel only — GUID: iga1401397706978
Ixiasoft
30.3.1. DMA Parameters (Basic)
Transfer Size
The parameter Width of the DMA Length Register specifies the minimum width of the DMA’s transaction length register, which can be between 1 and 32. The length register determines the maximum number of transfers possible in a single DMA transaction.
By default, the length register is wide enough to span any of the agent peripherals hosted by the read or write ports. Overriding the length register may be necessary if the DMA host port (read or write) hosts only data peripherals, such as a UART. In this case, the address span of each agent is small, but a larger number of transfers may be desired per DMA transaction. A smaller transfer width usually results in a faster FPGA frequency for the DMA Controller Core.
Burst Transactions
When Enable Burst Transfers is turned on, the DMA controller performs burst transactions on its host read and write ports. The parameter Maximum Burst Size determines the maximum burst size allowed in a transaction.
In burst mode, the length of a transaction must not be longer than the configured maximum burst size. Otherwise, the transaction must be performed as multiple transactions.
FIFO Depth
The parameter Data Transfer FIFO Depth specifies the depth of the FIFO buffer used for data transfers. Intel recommends that you set the depth of the FIFO buffer to at least twice the maximum read latency of the agent interface connected to the read host port. A depth that is too low reduces transfer throughput.
FIFO Implementation
This option determines the implementation of the FIFO buffer between the host read and write ports. Select Construct FIFO from Registers to implement the FIFO using one register per storage bit. This option has a strong impact on logic utilization when the DMA controller’s data width is large. See the Advanced Options section.
By default, the FIFO implementation uses the embedded memory blocks.