Overview

A tiny RAM expansion board offering 8Mbit (1M bytes) of memory storage accessible by the SPI 4-wire interface in a dual chip configuration. The two chips share the same SPI bus but are individually accessed by two separate chip-select pins.

Module provides full breakout of all SRAM pins including optional modes like hold, dual and quad SPI. Power supplied can be for a 2.5V or 3.3V interface.

Microcontrollers and boards like Arduino and Digilent often have very limited amounts of program memory leaving very little left over for storing user data such as graphics, audio or other user data. By using a RAM expansion module you can

• run more complex programs by keeping processor on-chip memory reserved for program variables.
• avoid wearing out FLASH memory which has a limited number of lifetime write cycles.

Compare the 1024 KB of RAM (1 megabyte) to:

• Arduino Uno = 2 KB
• Arduino Mega 2560 = 8KB
• Arduino Due = 96 KB

Pinout

Module is plug-in compatible with Digilent PMOD interface but can be used with any board by properly connecting the signals on the memory module.

1 - CS0n - active low chip select for memory 0

2 - MOSI

3 - MISO

4 - SCLK

5,11 - GND

6,12 - VDD

7 - CS1n - active low chip select for memory 1

8 - no connect (unused)

9 - SIO2 - serial I/O bit 2 for SPI quad (SDQ) mode

10 - HOLDn (SIO3) - Dual purpose. Active low HOLD pauses the transfer. For SDQ, this is I/O bit 3