Diff: main.cpp

Revision:

0:c0996e3989ce

diff -r 000000000000 -r c0996e3989ce main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Feb 22 14:14:17 2017 +0000
@@ -0,0 +1,83 @@
+/* Morse Code
+
+(c) Dr Craig A. Evans, University of Leeds
+
+A dot is 1 time unit
+A dash is 3 time units
+Space between parts of a letter is 1 unit
+Space between letters is 3 units
+Space between words is 7 units
+
+*/
+
+#include "mbed.h"
+
+DigitalOut red_led(p24);
+DigitalOut green_led(p23);
+DigitalOut blue_led(p22);
+
+void init_leds();
+void dot();
+void dash();
+void morse_s();
+void morse_o();
+void sos();
+
+// global variable for unit time in milli-seconds
+int g_time_unit_ms = 150;
+
+int main()
+{
+    init_leds();
+
+    while(1) {
+        sos();
+        wait_ms(7*g_time_unit_ms);  // space between words is 7 units
+    }
+}
+
+// LEDs are active low and so writing a 1 turns them off
+void init_leds()
+{
+    red_led.write(1);
+    green_led.write(1);
+    blue_led.write(1);
+}
+
+void dot()
+{
+    red_led.write(0);  // turn LED on
+    wait_ms(g_time_unit_ms);   // wait for 1 time unit
+    red_led.write(1);  // turn LED off
+}
+
+void dash() 
+{
+    red_led.write(0);  // turn LED on
+    wait_ms(3*g_time_unit_ms);   // A dash is 3 time units
+    red_led.write(1);  // turn LED off
+}
+
+void morse_s() {  // ...
+    dot();
+    wait_ms(g_time_unit_ms);  // space between parts of a letter is 1 unit
+    dot();
+    wait_ms(g_time_unit_ms);
+    dot(); 
+}
+
+void morse_o() {  // ---
+    dash();
+    wait_ms(g_time_unit_ms);  // space between parts of a letter is 1 unit
+    dash();
+    wait_ms(g_time_unit_ms);
+    dash(); 
+}
+
+void sos() { // ... --- ...
+    morse_s();
+    wait_ms(3*g_time_unit_ms);  // space between letters is 3 units
+    morse_o();
+    wait_ms(3*g_time_unit_ms);  // space between letters is 3 units
+    morse_s();        
+}
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