3

FORGE

and processing capabilities. As a developer, you
must always pay attention to how you use the
device’s memory and processor.
An Arduino device has a limited amount of
three types of memory:

• Flash Memory: Stores the Arduino bootloader
  and your compiled sketch.


• Static RAM: Used for variable storage.


• EEPROM (electrically erasable programmable
  read-only memory): Non-volatile memory you
  can use to store data while the Arduino is
  turned off.

The Arduino Uno, for example, has the
following memory footprint:

• 256kB of flash memory


• 2kB of static RAM


• 1kB of EEPROM memory

When you compile your sketch, the compiler
will inform you of how much memory your sketch
consumes, as shown in Figure 3. As you code
larger and more complicated sketches, or use more

libraries in your sketches, you must pay attention

to this data in order to ensure that your sketch will

run as coded on your selected Arduino device. In

the example shown, we’re only using 14% of flash

memory (program storage space) and 17% of static

RAM (dynamic memory) for my sketch, so we’re in

good shape (for now).

Sketch uses 4780 bytes (14%) of program storage

space. Maximum is 32256 bytes.

Global variables use 352 bytes (17%) of dynamic

memory, leaving 1696 bytes for local variables.

Maximum is 2048 bytes.

If your sketch exceeds the available memory on

the device, you must either re-factor the application

to make better use of the memory available to

you, or switch to another device that provides

more memory.

Left

If you’re ever unsure

about exactly what a

variable type means,

you can check the

Arduino language

reference at

hsmag.cc/VYrTRY

Arduino devices are inexpensive programmable

microcontrollers, and in order to meet its

imposed cost limitation, the devices have limited

memory and processing capabilities

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