NanoBoard 3000 - Independent SRAM

The NanoBoard 3000 includes independent Static RAM as part of the memory resources available to the on-board User FPGA device, or more specifically a programmed design therein. The term 'independent' is used in this case to distinguish this SRAM – which is interfaced using dedicated address and data lines – from the SRAM that is accessed over a common bus (also used to access on-board SDRAM, Flash memory and the USB Hub).

Independent SRAM available to an FPGA design.

The SRAM is provided in the form of two 4Mbit, high-speed CMOS SRAM devices. Each device is organized as 256K x 16 bits and powered by the motherboard's 3.3V supply.

The devices are accessed separately, giving two distinct 256K x 16-bit storage areas (512KByte each, 1MByte in total).

Although the devices require 18 address lines (SRAM_A[17..0]), the interface makes provision for a nineteenth address line (SRAM_A18), giving the flexibility to accommodate 512 x 16-bit devices, should they require to be fitted.

Location on Board

The independent SRAM devices (designated U14 and U15) are located on the solder side of the board, above the overlay graphic of the SD card.

Schematic Reference

The independent SRAM device can be found on Sheet 29 (SRAM_256Kx16_TSOP44.SchDoc, entitled 256K x 16-Bit SRAM) of the motherboard schematics.

Design Interface Component

Table 1 summarizes the available design interface components that can be placed from the FPGA NB3000 Port-Plugin.IntLib for access to, and communications with, the independent SRAM.