Hello all,
virtmem is an Arduino (and Teensyduino!) library that makes it easy to extend the limited RAM available on microcontrollers with 'virtual memory'. To do so, virtmem provides a simple interface to use external memory sources such as an SD card or SPI RAM chip which resembles working with 'regular' memory.
Some of its main features are:
And a small demonstration that uses an SD card as memory source:
The project is hosted on github: https://github.com/rhelmus/virtmem
A detailed manual with more info can be found here: http://rhelmus.github.io/virtmem/index.html
Most of the development was done on Teensy 3.X boards. This is the first release, but already pretty feature complete. Nevertheless, any feedback (questions, suggestions, bugs etc) is welcome!
virtmem is an Arduino (and Teensyduino!) library that makes it easy to extend the limited RAM available on microcontrollers with 'virtual memory'. To do so, virtmem provides a simple interface to use external memory sources such as an SD card or SPI RAM chip which resembles working with 'regular' memory.
Some of its main features are:
- Extend the available memory with kilobytes, megabytes or even gigabytes
- Supports SPI RAM (23LC series from Microchip), SD cards and RAM from a computer connected through serial
- Easy C++ interface that closely resembles regular data access
- Memory page system to speed up access to virtual memory
- New memory interfaces can be added easily
And a small demonstration that uses an SD card as memory source:
Code:
#include <Arduino.h>
#include <SdFat.h>
#include <virtmem.h>
#include <alloc/sd_alloc.h>
// Simplify virtmem usage
using namespace virtmem;
// Create virtual a memory allocator that uses SD card (with FAT filesystem) as virtual memory pool
// The default memory pool size (1 MB) is used.
SDVAlloc valloc;
SdFat sd;
struct MyStruct { int x, y; };
void setup()
{
// Initialize SdFatlib
if (!sd.begin(9, SPI_FULL_SPEED))
sd.initErrorHalt();
valloc.start(); // Always call this to initialize the allocator before using it
// Allocate a char buffer of 10000 bytes in virtual memory and store the address to a virtual pointer
VPtr<char, SDVAlloc> str = valloc.alloc<char>(10000);
// Set the first 1000 bytes to 'A'
memset(str, 'A', 1000);
// array access
str[1] = 'B';
// Own types (structs/classes) also work.
VPtr<MyStruct, SDVAlloc> ms = valloc.alloc<MyStruct>(); // alloc call without parameters: use automatic size deduction
ms->x = 5;
ms->y = 15;
}
void loop()
{
// ...
}The project is hosted on github: https://github.com/rhelmus/virtmem
A detailed manual with more info can be found here: http://rhelmus.github.io/virtmem/index.html
Most of the development was done on Teensy 3.X boards. This is the first release, but already pretty feature complete. Nevertheless, any feedback (questions, suggestions, bugs etc) is welcome!