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SIMM

IMAGE SIMM RAM is a library for the Arduino MEGA 2560 that can be used to control 30 pin SIMM RAM modules.

First, Why ?!

I made this library mostly for fun, but I also had a use for it. I needed to show changing images on a display, but it would take 2 or 3 seconds to update because I was loading them from an SD card. But with the ram, I can just load the images to RAM on startup and read them very quickly when I need them !

Pros and cons:

Pros:

  • VERY fast !
  • A lot of storage compared to the internal ram of the arduino (can be up to 16Mb)
  • No other components needed except the RAM module itself

Cons:

  • Takes a bit of CPU power aprox. 16 times per second to refresh the RAM
  • Uses a lot of wires (27 wires to be exact)

How to use the library

You will need:

  • An Arduino MEGA 2560
  • A 30 pin SIMM RAM module
  • Wires to connect it all up

The schematic:

  • DQ0 - DQ7 -> PORTL
  • A0 - A7 -> PORTA
  • A8 -> Pin 37
  • A9 -> Pin 36
  • A10 -> Pin 35
  • A11 -> Pin 34
  • CAS -> Pin 32
  • WE -> Pin 31
  • RAS -> Pin 30

SIMM_PINOUT ARDUINO_PORTS

Functions:

void begin();                                                                   // Initialize RAM
void stop();                                                                    // Stop RAM
byte read(uint16_t row, uint16_t column);                                       // Read a byte from RAM
void write(uint16_t row, uint16_t column, byte data);                           // Write a byte to RAM
void readBlock(uint16_t row, uint16_t column, uint16_t length, byte array[]);   // Read a block of bytes from RAM
void writeBlock(uint16_t row, uint16_t column, byte array[]);                   // Write a block of bytes to RAM

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SIMM RAM library for the Arduino MEGA 2560

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