Stratix® 10 Hard Processor System Technical Reference Manual

ID 683222
Date 8/15/2024
Public
Document Table of Contents

7.3.2.1. FPGA-to-SDRAM direct (Cache Non-Allocate)

The interface from the FPGA to the SDRAM directly is AXI* 4. These transactions route directly to the EMIF circumventing the CCU and are not cached. You must manage coherency in software because the CCU is not involved with this traffic. Transactions can be privileged or non-privileged depending on Memory Allocation.

Reads

Cache is not looked up. Read data is returned directly from SDRAM.
ATTRIBUTE VALUE NOTE
ARDOMAIN[1:0] ‘b00 Non-shareable. (non-coherent, non-snooping)
ARBAR[1:0] ‘b00 Normal access, respecting barriers
ARSNOOP[3:0] ‘b0000 ReadNoSnoop
ARCACHE[3:0] ‘b0010 or ‘b0011

Normal Non-cacheable Non-bufferable (or Normal Non-cacheable Bufferable)

ARPROT[2:0] ‘b001 or ‘b000

Privileged access. Secure access. Data access

(could be ‘b000 for Unprivileged access)

ARLEN[7:0]

The burst length for:

WRAP burst type must be 1, 2, 4, 8 or 16 transfers.

INCR burst type is 1 to 256 transfers.

ARSIZE[2:0] The number of bytes in a transfer must be equal to the data bus width (32, 64, or 128 bits)
ARBURST[1:0] ‘b01 or ‘b10 Must be INCR(‘b01) or WRAP(‘b10)
ARLOCK[1:0] ‘b00 Must be normal access
ARQOS Quality of Service. QoS identifier sent for each transaction. Implemented only in AXI4.

Writes

Cache is not looked up. Write data is stored directly to SDRAM.
ATTRIBUTE VALUE NOTE
AWDOMAIN[1:0] ‘b00 Non-shareable. (non-coherent, non-snooping)
AWBAR[1:0] ‘b00 Normal access, respecting barriers
AWSNOOP[2:0] ‘b000 WriteNoSnoop
AWCACHE[3:0] ‘b0010 or ‘b0011

Normal Non-cacheable Non-bufferable

(or Normal Non-cacheable Bufferable)

AWPROT[2:0] ‘b001 or ‘b000

Privileged access. Secure access. Data access

(could be ‘b000 for Unprivileged access)

AWLEN[7:0]

The burst length for:

WRAP burst type must be 1, 2, 4, 8 or 16 transfers.

INCR burst type is 1 to 256 transfers.

AWSIZE[2:0] The number of bytes in a transfer must be equal to the data bus width (32, 64, or 128 bits)
AWBURST[1:0] ‘b01 or ‘b10 Must be INCR(‘b01) or WRAP(‘b10)
AWLOCK[1:0] ‘b00 Must be normal access
AWQOS Quality of Service. QoS identifier sent for each transaction. Implemented only in AXI4.