外部のライブラリを利用する場合に宣言します。
Arduinoにおける文法は標準C言語 と特に変わりはありません。
● Example from Arduino Web Site
[c]
/*
This example includes a library that is used to put data into the program space <em>flash</em> instead of <em>ram</em>.</pre>
<pre>This saves the ram space for dynamic memory needs and makes large lookup tables more practical.
*/
#include <avr/pgmspace.h>
prog_uint16_t myConstants[] PROGMEM = {0, 21140, 702 , 9128, 0, 25764, 8456,
0,0,0,0,0,0,0,0,29810,8968,29762,29762,4500};
[/c]
