SFLASH-AHB
Universal Serial Flash Controller

The SFLASH-AHB core is a versatile serial flash memory controller that allows a system to easily detect and access an attached flash device, or directly boot from it. The controller core supports the SPI protocols used by all major Flash device vendors and is compatible with JeDEc’s eXtended SPI (xSPI), Xccela, and (optionally) Hyperbus standards.

The core allows the system to interface with one or more serial flash devices in one of the following modes: a) in Slave mode by accessing its registers via an AHB slave interface; b) in DMA mode where the system programs the internal DMA engine and then the core accordingly drives its AHB master interface; c) in eXecute In-Place (XIP) mode where the core allows the system to directly access the SPI memory address space via an AHB slave interface; d) in Boot-Image copy mode where after reset the core will autonomously copy an amount of data (boot-image) from the SPI memory to the AHB address space (e.g. on a shadow RAM or DRAM) using its AHB master interface).

The core can work with single, dual, quad, twin-quad, and octal SPI flash devices. To enable use with flash devices from different vendors, the core offers two ways of configuring the device-specific parameters: a) via registers, where the system is responsi-ble to identify the connected flash device and program the appropriate values to the core's registers; and b) by using the auto-configuration feature, where the core will autonomously identify the connected flash device and program itself accordingly. The auto-configuration functionality uses a user-provided memory that stores a list of automatically identifiable devices along with their features. 

The SFLASH-AHB can be easily configured to match different application requirements. The data and address width of the AHB interfaces, instantiation of the DMA engine and the auto-configuration logic, the maximum number of Flash devices that the core supports, and the reset values for all configuration registers, are some of the design parameters that can be controlled by means of simple Verilog defines. 

This core has been designed with industry best practices. It is LINT-clean and scan ready, it has been verified through rigorous verification, and it is silicon-proven.  

Support

The core as delivered is warranted against defects for ninety days from purchase. Thirty days of phone and email technical support are included, starting with the first interaction. Additional maintenance and support options are available.

Deliverables

  • Verilog source or FPGA netlist

  • User Documentation

  • Testbench and sample synthesis and simulation scripts

The SFLASH-AHB can be mapped to any ASIC technology or FPGA device (provided sufficient silicon resources are available). The following table provides sample implementation data. Please contact CAST to get characterization data for your target con-figuration and technology.

Configuration Technology Area
(eq. Gates)
Clock Freq.
(MHz)
XIP off, DMA off, Auto-config. off TSMC 16nm 8,600 AHB: 500
SPI: 166
XIP on, DMA off, Auto-config. off 11,500
XIP on, DMA off, Auto-Config on 13,400
XIP on, DMA on, Auto-config. on 16,661

The SFLASH-AHB can be mapped to any Intel FPGA device (provided sufficient silicon resources are available). The following table provides sample implementation data. Please contact CAST to get characterization data for your target configuration and technology.

Configuration Technology FPGA
Resources
Clock Freq.
(MHz)
XIP on, DMA off, Auto-config. off Arria 10 GX
5AGXBB3D4F35C5
966 ALMs, 256 Mem. bits AHB: 250, SPI: 167
XIP on, DMA on, Auto-config. on 1,479 ALMs, 256 Mem. bits

The SFLASH-AHB can be mapped to any Xilinx FPGA device (provided sufficient silicon resources are available). The following table provides sample implementation data. Please contact CAST to get characterization data for your target configuration and technology.

Configuration Technology FPGA
Resources
Clock Freq.
(MHz)
XIP on, DMA off, Auto-config. off Kintex-7 7k420t-ffg1156-2 1,200 LUTs AHB: 250, SPI: 100

Related Content

Features List

Universal Serial NOR and NAND Flash Controller

  • Compatible to all SPI protocols used by the major vendors. 
  • Supports xSPI (JEDEC’s JESD251), Xccela, and optionally Hyperbus standards 
  • Run-time programmable parameters: 
    • Single, Dual, Quad, Twin-Quad and Octal SPI lanes
    • Single and Dual Transfer Rate (STR and DTR) SPI lanes
    • Bit-length and number of SPI lanes used for command, address, latency (dummy cycle) and data
    • Command encoding

Flexible Flash Access Modes

  • XIP: Allows AHB bus masters to read directly from the flash with zero software overhead 
  • DMA: Optional DMA engine can be programmed to transfer data from/to system to/from the Flash device
  • Boot-Image Copy:After reset the core uses its DMA engine to autonomously copy an amount of data from Flash to the AHB address space
  • Slave Mode: System accesses core registers to transfer data to/from the Flash 

Easy Integration & Operation

  • Flash Device-independent: the flash device parameters can be set in the following ways: 
    • Automatically after reset: a list of automatically identifiable devices is provided to the core in an external memory 
    • At run time via configuration registers programming 
    • At synthesis time via Verilog defines for reset values of all configuration registers
  • Zero software overhead with XIP and optional auto-configuration
  • 32-bit and 64-bit AHB bus interfaces. Data-bus widths are configurable at synthesis time.

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