main.cpp

00001 #include "mbed.h"
00002 
00003 DigitalIn button_A(p29);
00004 DigitalIn button_B(p28);
00005 DigitalIn button_C(p27);
00006 DigitalIn button_D(p26);
00007 
00008 DigitalOut red_led(p24);
00009 DigitalOut green_led(p23);
00010 DigitalOut blue_led(p22);
00011 
00012 void init_buttons();
00013 void init_leds();
00014 
00015 int main()
00016 {
00017     init_buttons();  // turn off internal pull-up/pull-down resistors
00018     init_leds();     // tursn off the LEDs
00019 
00020     while(1) {
00021 
00022         // check if button A pressed
00023         if ( button_A.read() == 1) {
00024             // writing a 1 turns the LED off, 0 makes it turn on (active-low)
00025             red_led.write(0);  // if it is, turn the red LED on
00026         } else if (button_B.read() == 1) { // check if B pressed
00027             green_led.write(0);  // if it is, turn the green LED on
00028         } else if ( button_C.read() == 1) { // check if C pressed
00029             blue_led.write(0);  // if it is, turn the blue LED on
00030         } else {
00031             // if no buttons pressed, ensure all the LEDs are off
00032             red_led.write(1);
00033             green_led.write(1);
00034             blue_led.write(1);
00035         }
00036 
00037         wait(0.1);  // small delay
00038 
00039     }
00040 }
00041 
00042 void init_buttons()
00043 {
00044     // PCB has external pull-down resistors so turn the internal ones off
00045     // (default for DigitalIn)
00046     button_A.mode(PullNone);
00047     button_B.mode(PullNone);
00048     button_C.mode(PullNone);
00049     button_D.mode(PullNone);
00050 }
00051 
00052 void init_leds()
00053 {
00054     // LEDs are common anode (active-low) so writing a 1 will turn them off
00055     red_led.write(1);
00056     green_led.write(1);
00057     blue_led.write(1);
00058 
00059     // this syntax is equivalent
00060     //red_led = 1;
00061     //green_led = 1;
00062     //blue_led = 1;
00063 }
00064