Diff: main.cpp

Revision:

0:e90fdaaa28ef

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Apr 01 00:48:37 2011 +0000
@@ -0,0 +1,57 @@
+// dimmed kitt LED blinking
+//   the question was how to enable dimming on multiple digital led the same time.
+//   it could be done simpler with math/sin, yet it I found it more fun
+#include "mbed.h"
+
+DigitalOut led[4] = { LED1, LED2, LED3, LED4 };
+int  dim[4] = { 1, 1, 1, 1 };  // 1:always on N: darker, I use 1..100
+
+void Dim( ) {
+   for (long int i=0; i < 10000; ++i) {          // repeat a few times just to slow down
+      for (int i2=0; i2<4; ++i2) {
+         led[i2] = (((i%dim[i2])==0) ? 1 : 0);
+      }
+   }
+}
+
+void Update1( int i ) {      // i:1..99
+      dim[0] = i;
+      dim[1] = (i-33)%200 + 1;
+      dim[2] = (i-66)%200 + 1;
+      dim[3] = i-100; // could be (i-100)%200 + 1;
+}
+
+void Update2( int i ) {      // i:1..99
+      dim[0] = 100-i;
+      dim[1] = (i-66)%200 + 1;
+      dim[2] = (i-33)%200 + 1;
+      dim[3] = i;
+}
+
+/* phase-shift the LED dimming 1..100 positive, 101..199 going back
+that work, but the above is easier to understand
+int Rate( int i ) {                 // calculate dim rate, convert 1..200 to 1..100..1
+    return (i<100) ? i : (200-i);
+}
+void Update( int i ) {
+      dim[0] = Rate( i%200 + 1 );
+      dim[1] = Rate( (i+(i<100?-33:33))%200 + 1);
+      dim[2] = Rate( (i+(i<100?-66:66))%200 + 1);
+      dim[3] = Rate( (i+100)%200 + 1);
+}
+*/
+
+int main() {
+    while(1) {
+        for (int i = 1; i <100; ++i )        // to
+        {
+            Update1( i );
+            Dim( );
+        }
+        for (long int i = 1; i <100; ++i )   // and back
+        {
+            Update2( i );
+            Dim( );
+        }
+    }
+}