static

1/* RandomWalk
2      Paul Badger 2007
3      RandomWalk wanders up and down randomly between two
4      endpoints. The maximum move in one loop is governed by
5      the parameter "stepsize".
6      A static variable is moved up and down a random amount.
7      This technique is also known as "pink noise" and "drunken walk".
8    */
9
10    #define randomWalkLowRange -20
11    #define randomWalkHighRange 20
12    int stepsize;
13
14    int thisTime;
15    int total;
16
17    void setup() {
18      Serial.begin(9600);
19    }
20
21    void loop() {
22      //  test randomWalk function
23      stepsize = 5;
24      thisTime = randomWalk(stepsize);
25      Serial.println(thisTime);
26      delay(10);
27    }
28
29    int randomWalk(int moveSize) {
30      static int place; // variable to store value in random walk - declared static so that it stores
31      // values in between function calls, but no other functions can change its value
32
33      place = place + (random(-moveSize, moveSize + 1));
34
35      if (place < randomWalkLowRange) {                               // check lower and upper limits
36        place = randomWalkLowRange + (randomWalkLowRange - place);    // reflect number back in positive direction
37      }
38      else if (place > randomWalkHighRange) {
39        place = randomWalkHighRange - (place - randomWalkHighRange);  // reflect number back in negative direction
40      }
41
42      return place;
43    }