main.cpp

00001 /* See
00002  * http://lancaster-university.github.io/microbit-docs/advanced/
00003  * for docs about using the micro:bit library
00004 */
00005 #ifndef M_PI
00006 #define M_PI           3.14159265358979323846
00007 #endif
00008 
00009 #include "MicroBit.h"
00010 
00011 // a,b line normal vector coordinates, should be normalized, a^2 + b^2 = 1 
00012 // returns if distance of point at coordinates x, y and vector line does not 
00013 // exceed given range
00014 bool inRange(float a, float b, float x, float y, float range = 0.5)
00015 {
00016     return abs(a*x + b*y) < range;
00017 }
00018 // answer if the LED in row, column should be lit or turned off
00019 bool isLit(float a, float b, int row, int column)
00020 {
00021     float x = column - 2;
00022     float y = 2 - row;
00023     return inRange(a,b,x,y);
00024 }
00025 
00026 float deg2rad(int deg)
00027 {
00028     return (float) deg * M_PI / 180;
00029 }
00030 
00031 MicroBit uBit;
00032 
00033 int main()
00034 {
00035 
00036 
00037     uBit.init();
00038 
00039     while (true) {
00040         int heading = uBit.compass.heading();
00041         //uBit.serial.printf("%d\r\n", heading);
00042         
00043         float angle = M_PI / 2 - deg2rad(heading); //calculate angle of displayed line
00044         float a = sin(angle); //calculate line normal vector parameters a, b
00045         float b = cos(angle); 
00046         
00047         for (int row = 0; row < 5; row++) {
00048             for (int col = 0; col < 5; col++) {
00049                 uBit.display.image.setPixelValue(col,row,isLit(a, b, row, col) ? 255 : 0);
00050             }
00051         }
00052         
00053         uBit.sleep (100);
00054     }
00055 }
00056