Arria® 10 or Cyclone® 10 GX Avalon® Memory-Mapped (Avalon-MM) DMA Interface for PCI Express* Solutions User Guide
5.1.7.1. Avalon-ST Descriptor Status Interface
When DMA module completes the processing for one Descriptor Instruction, it returns DMA Status to the Descriptor Controller via the following interfaces.
| Signal Name |
Direction |
Description |
|---|---|---|
| RdAstTxData_o[31:0] |
Output |
Drives status information to the Descriptor Controller component. Refer to DMA Status Bus table below for more information |
| RdAstTxValid_o |
Output |
When asserted, indicates that the data is valid. |
| Signal Name |
Direction |
Description |
|---|---|---|
| WrAstTxData_o[31:0] |
Output |
Drives status information to the Descriptor Controller component. Refer to DMA Status Bus table below for more information about this bus. |
| WrAstTxValid_o |
Output |
When asserted, indicates that the data is valid. |
| Bits |
Name |
Description |
|---|---|---|
| [31:0] |
Source Low Address | Low-order 32 bits of the DMA source address. The address boundary must align to the 32 bits so that the 2 least significant bits are 2'b00. For the Read DMA module, the source address is the PCIe domain address. For the Write DMA module, the source address is the Avalon-MM domain address. |
| [63:32] |
Source High Address | High-order 32 bits of the source address. |
| [95:64] |
Destination Low Address | Low-order 32 bits of the DMA destination address. The address boundary must align to the 32 bits so that the 2 least significant bits have the value of 2'b00. For the Read DMA module, the destination address is the Avalon-MM domain address. For the Write DMA module the destination address is the PCIe domain address. |
| [127:96] |
Destination High Address | High-order 32 bits of the destination address. |
| [145:128] |
DMA Length | Specifies DMA length in dwords. The length must be greater than 0. The maximum length is 1 MB - 4 bytes. |
| [153:146] |
DMA Descriptor ID | Specifies up to 128 descriptors. |
| [158:154] |
Reserved | — |
| [159] | Immediate Write | When set to 1'b1, the Write DMA Engine performs an Immediate Write. The Immediate Write provides a fast mechanism to send a Write TLP upstream. The descriptor stores the 32-bit payload, replacing the Source Low Address field of the descriptor. |