Diff: main.cpp

Revision:

0:bbe54468c896

Child:

1:d6cbfa3636c7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat May 24 12:20:47 2014 +0000
@@ -0,0 +1,79 @@
+/**************************************************************************
+*                                                                         *
+*   This example builds on 01_Simple_Segments by introducing an example   *
+*   of how brightness might be achieved.                                  *
+*                                                                         *
+*   In this case the right hand LED is displayed dimmer than the left.    *
+*   With more logic it would be possible to adjust te brightness of       *
+*   individual segments within the display.                               *
+*                                                                         *
+**************************************************************************/
+
+#include "mbed.h"
+
+uint8_t left = 0;
+uint8_t right = 1;
+
+uint8_t brightness = 100;
+
+//The 8 segment outputs and com to switch between the LEDs
+DigitalOut seg_a(P1_23), seg_b(P1_28), seg_c(P0_16), seg_d(P1_31), seg_e(P1_13), seg_f(P1_16), seg_g(P1_19), seg_p(P0_23), com(P1_25);
+
+/******************************************************
+*   Set each of the segments for a desired LED        *
+******************************************************/
+void SetSegments(uint8_t led, uint8_t a, uint8_t b, uint8_t c, uint8_t d, uint8_t e, uint8_t f, uint8_t g, uint8_t p)
+{
+    //Set left LED
+    com = left;
+    
+    //Switch off all segments (1 means off!)
+    seg_a = seg_b = seg_c = seg_d = seg_e = seg_f = seg_g = seg_p = 1;
+    
+    //Set desired LED to update
+    com = led;
+    
+    //Switch on the desired segments a number of times based on the brightness required
+    for(uint8_t i = 0; i < brightness; i++) 
+    {
+        seg_a = 1 - a; //setting a segment to 1 means off 
+        seg_b = 1 - b; //so invert all requested segment values
+        seg_c = 1 - c;
+        seg_d = 1 - d;
+        seg_e = 1 - e;
+        seg_f = 1 - f;
+        seg_g = 1 - g;
+        seg_p = 1 - p;
+    }
+    
+    //Switch off all the segments a remaining number of times to reach 100 updates
+    for(uint8_t i = 0; i < 100 - brightness; i++) 
+    {
+        seg_a = seg_b = seg_c = seg_d = seg_e = seg_f = seg_g = seg_p = 1;
+    }
+    
+    //Finally switch off all segments again, we must do this otherwise when
+    //switching com the segments could be momentarily duplicated from this led.
+    seg_a = seg_b = seg_c = seg_d = seg_e = seg_f = seg_g = seg_p = 1;
+
+}
+
+/******************************************************
+*   Main loop repeatedly updates each of the LEDs     *
+******************************************************/
+int main()
+{
+    for(;;) 
+    {
+        //Set the display to read '42'
+        
+        //The 4 will be displayed at full brightness
+        brightness = 100;
+        SetSegments(left,  0,1,1,0,0,1,1,0); //4
+        
+        //The 2 will be displayed much more faintly
+        brightness = 5;
+        SetSegments(right, 1,1,0,1,1,0,1,0); //2
+    }
+}
+