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RAM Controller – National Semiconductor® RAM Controller

RAMC Brochure

National LogoThe RAM Controller (RAMC) provides connectivity between an AMBA 2 AHB and a synchronous RAM (SRAM). It features single-cycle, pipelined access to 32-bit SRAM and supports 8, 16, and 32-bit data accesses. It is the same RAM Controller IP proven in high-volume devices from National Semiconductor.

The host interface of the RAMC complies with the AMBA 2 AHB protocol. The AHB data bus width is 32 bits, while the AHB address bus width is configurable (3–32 bits). The RAMC does not generate wait states on the AHB; each data phase is one clock clock cycle.

The RAMC connects to a synchronous RAM through a generic RAM interface. The RAM must support byte-write operation and can be implemented either as a single 32-bit RAM or as four 8-bit RAMs.

The RAMC does not pass the 2 least significant bits of the AHB address (HADDR [1:0]) to the RAM address output. Therefore, byte-addresses on the AHB address bus become 32-bit word addresses at the RAM interface. For write accesses, the RAMC automatically generates the correct RAM byte write enables according to the values of AHB signals HADDR[1:0] and HSIZE[2:0].

For read accesses, the RAMC always reads a 32-bit word and returns the full 32 bits on HRDATA[31:0].

If a read access occurs while a write access to the same address is pending, the RAMC returns the internally registered write data for the byte(s) that have not yet been written to the RAM.

 

Block Diagram

FEATURES
  • AMBA 2 AHB compliant host interface
  • Single-cycle pipelined read/write accesses to 32-bit SRAM
  • 8, 16, or 32-bit accesses
  • Configurable address width
  • SRAM can be implemented as single 32-bit RAM or four 8-bit RAMs
  • Little endian data interface
  • Local clock gating for minimal power consumption
DELIVERABLES

The deliverables for the RAM Controller include:

  • Synthesizable Verilog source code
  • Documentation
  • Scripts to synthesize the RAM Controller with common EDA tools

For more information about RAM Controllers, please conatct us at info@ip-extreme.com.