Revision 0:dae51f35ea20, committed 2010-12-20

Comitter:

neilp

Date:

Mon Dec 20 22:30:17 2010 +0000

Commit message:

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Dec 20 22:30:17 2010 +0000
@@ -0,0 +1,60 @@
+#include "mbed.h"
+
+// Use a simple PWM program to fade the 4 on-board LEDs
+//  - Each LED fades on and off at different rates
+//  - Uses on-board LEDs only, no external HW or PWM hardware required
+//  - LED brightness is a factor of the duty cycle, i.e. how long the LED
+//    is turned on during a given loop
+
+// Setup the LED outputs and assign variables
+DigitalOut led1(LED1);
+DigitalOut led2(LED2);
+DigitalOut led3(LED3);
+DigitalOut led4(LED4);
+
+int pwmloop = 0 ;         // loop counter from 0 to 255 and repeat
+int led_value[4];        // array of led brightness
+int led_change[4];        // array of led brightness change values
+
+int i;                    // loop variable
+
+int main() {
+    led_value[0] = 3;    // init counter value
+    led_value[1] = 5;
+    led_value[2] = 7;
+    led_value[3] = 9;
+
+    led_change[0] = 5;    // set rate of led brightness change per led
+    led_change[1] = 6;
+    led_change[2] = 7;
+    led_change[3] = 8;
+            
+    while(1) {
+        
+        for (pwmloop = 0; pwmloop < 256; pwmloop++) {
+            // Drive LEDs, turned on when less than pwnloop, 0 = full off, 255 = full on
+            if (led_value[0] < pwmloop) { led1 = 1; } else { led1 = 0; }
+            if (led_value[1] < pwmloop) { led2 = 1; } else { led2 = 0; }
+            if (led_value[2] < pwmloop) { led3 = 1; } else { led3 = 0; }
+            if (led_value[3] < pwmloop) { led4 = 1; } else { led4 = 0; }
+
+            // short wait - control over light fading speed, experiment with larger
+            //              delays to show how the PWM is working.
+            wait_us(20);
+        }
+
+        // Update LED brightness value at the end of the pwm loop
+        for (i = 0; i<4; i++) {
+            led_value[i] += led_change[i];
+            
+            // check range is withing 0 to 255, if not change direction
+            if (led_value[i] > 255) {
+                led_change[i] = -led_change[i];
+            }
+            if (led_value[i] < 0) {
+                led_change[i] = -led_change[i];
+            }            
+        }
+    }
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.lib	Mon Dec 20 22:30:17 2010 +0000
@@ -0,0 +1,1 @@
+http://mbed.co.uk/svn/libraries/mbed/trunk@2
\ No newline at end of file