random number bafflement

Projects Programming
1

in the past, this bit of code in void setup() played back one of 15 audio files in my audio files root directory on bootup:

    pinMode(A0, INPUT ); randomSeed(analogRead(A0));
    sendCommand(CMD_PLAY_W_INDEX, 0X030000 + random(1, 15)); // play on reset 1 of 15 files in root folder

then it stopped working. now it plays file 1 or 8 only.

this random number test program:

void setup()
{
  Serial.begin(9600);
  pinMode(A0, INPUT ); randomSeed(analogRead(A0));
}

void loop()
{
  int c; c = random(1, 15); Serial.print(c); delay(1000); Serial.println();
}

produces this result:

8
14
9
6
2
7
4
10
5
3
4
12
4
3
7
9
11
5
14
12
14

this change, to reflect the way my void setup works:

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  pinMode(A0, INPUT ); randomSeed(analogRead(A0));
  int c; c = random(1, 15); Serial.print(c); delay(1000); Serial.println();
}

produces:

1
8
8
8
8
1
1
1
8
1
1
8
8
1
8
8
1
8
8
1
8
8

what is happening, to make random seed generate the same two numbers?

2

You're only supposed to seed it once. You're doing it every time just before calling random(). RTFM!

Also, putting multiple statements on one line is bad form.

3

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