Arria® 10 or Cyclone® 10 GX Avalon® Memory-Mapped (Avalon-MM) DMA Interface for PCI Express* Solutions User Guide
5.1.6. 32-Bit Control Register Access (CRA) Slave Signals
The CRA interface provides access to the control and status registers of the Avalon-MM bridge. This interface has the following properties:
- 32-bit data bus
- Supports a single transaction at a time
- Supports single-cycle transactions (no bursting)
| Signal Name |
Direction |
Description |
|---|---|---|
| CraRead_i |
Input |
Read enable. |
| CraWrite_i |
Input |
Write request. |
| CraAddress_i[13:0] |
Input |
An address space of 16 KB is allocated for the control registers. Avalon® -MM slave addresses provide address resolution down to the width of the slave data bus. Because all addresses are byte addresses, this address logically goes down to bit 2. Bits 1 and 0 are 0. To read or write individual bytes of a DWORD, use byte enables. For example, to write bytes 0 and 1, set this signal to 4'b0011. An address space of 32 KB is allocated for the control registers. Avalon® -MM slave addresses provide address resolution down to the width of the slave data bus. Because all addresses are byte addresses, this address logically goes down to bit 2. Bits 1 and 0 are 0. To read or write individual bytes of a DWORD, use byte enables. For example, to write bytes 0 and 1, set this signal to 4'b0011. |
| CraWriteData_i[31:0] |
Input |
Write data. The current version of the CRA slave interface is read-only. Including this signal as part of the Avalon-MM interface, makes future enhancements possible. |
| CraReadData_o[31:0] |
Output |
Read data lines. |
| CraByteEnable_i[3:0] |
Input |
Byte enable. |
| CraWaitRequest_o |
Output |
Wait request to hold off additional requests. |
| CraChipSelect_i |
Input |
Chip select signal to this slave. |
| CraIrq_o |
Output |
Interrupt request. A port request for an Avalon-MM interrupt. |