External Memory Interface Handbook Volume 3: Reference Material

ID 683841
Date 7/24/2019
Document Table of Contents

6.2. SDRAM Controller Subsystem Block Diagram

The SDRAM controller subsystem connects to the MPU subsystem, the L3 interconnect, and the FPGA fabric. The memory interface consists of the SDRAM controller, the physical layer (PHY), control and status registers (CSRs), and their associated interfaces.
Figure 146. SDRAM Controller Subsystem High-Level Block Diagram

SDRAM Controller

The SDRAM controller provides high performance data access and run-time programmability. The controller reorders data to reduce row conflicts and bus turn-around time by grouping read and write transactions together, allowing for efficient traffic patterns and reduced latency.

The SDRAM controller consists of a multiport front end (MPFE) and a single-port controller. The MPFE provides multiple independent interfaces to the single-port controller. The single-port controller communicates with and manages each external memory device.

The MPFE FPGA-to-HPS SDRAM interface port has an asynchronous FIFO buffer followed by a synchronous FIFO buffer. Both the asynchronous and synchronous FIFO buffers have a read and write data FIFO depth of 8, and a command FIFO depth of 4. The MPU subsystem 64-bit AXI port and L3 interconnect 32-bit AXI port have asynchronous FIFO buffers with read and write data FIFO depth of 8, and command FIFO depth of 4.


The DDR PHY provides a physical layer interface for read and write memory operations between the memory controller and memory devices. The DDR PHY has dataflow components, control components, and calibration logic that handle the calibration for the SDRAM interface timing.

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