L-Tile and H-Tile Avalon® Memory-mapped Intel® FPGA IP for PCI Express* User Guide
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6.1.1.1.1. Read Data Mover
The Read Data module sends memory read TLPs. It writes the completion data to an external Avalon-MM interface through the high throughput Read Master port. This data mover operates on descriptors the IP core receives from the DMA Descriptor Controller.
The Read DMA Avalon-MM Master interface performs the following functions:
1. Provides the Descriptor Table to the Descriptor Controller
The Read Data Mover sends PCIe* system memory read requests to fetch the descriptor table from PCIe* system memory. This module then writes the returned descriptor entries in to the Descriptor Controller FIFO using this Avalon-MM interface.
2. Writes Data to Memory Located in Avalon-MM Space
After a DMA Read finishes fetching data from the source address in PCIe* system memory, the Read Data Mover module writes the data to the destination address in Avalon-MM address space via this interface.
Signal Name |
Direction |
Description |
---|---|---|
rd_dma_write_o |
Output |
When asserted, indicates that the Read DMA module is ready to write read completion data to a memory component in the Avalon-MM address space. |
rd_dma_address_o[63:0] |
Output |
Specifies the write address in the Avalon-MM address space for the read completion data. |
rd_dma_write_data_o[255:0] |
Output |
The read completion data to be written to the Avalon-MM address space. |
rd_dma_burst_count_o[4:0] |
Output |
Specifies the burst count in 256-bit words. This bus is 5 bits for the 256-bit interface. |
rd_dma_byte_enable_o[31:0] |
Output |
Specifies which DWORDs are valid. |
rd_dma_wait_request_i |
Input |
When asserted, indicates that the memory is not ready to receive data. |