How to effectively generate random number with PICAXE 08M2

picaxe

I'm wondering how to effectively generate random numbers with my PICAXE 08M2. The following is my code:

; Inputs
symbol push_red = C.1 ; In 1
symbol push_buzzer = C.3; In 3

; Outputs
symbol buzzer = C.2; Out 2
symbol led_red = C.4;

symbol action = b0
symbol randnum = w5; 
symbol randbit = w6; 

main:

    FOR action = 1 TO 5
        RANDOM randnum
        LET randbit = randnum // 10
        IF randnum > 4 THEN
            PAUSE 500
            low led_red
            pause 500
            high led_red
        ELSE
            SOUND buzzer,(100, 100)
        ENDIF
    NEXT action

    SOUND buzzer,(120, 200)

Even though I'm generating a new random number with every loop, the result is always the same: LEDs light up, no sound generated. I've read some articles about dividing randnum by an appropriate number, but not sure how that works.

Best Answer

Like Dave says: you're using the wrong variable in the IF statement.

IF randnum > 4 THEN

should be 

IF randbit > 4 THEN

As I understand from another question randnum is in the range 0..65535, then the probability that it's less than 5 is less than 1 in 10 000. So if you repeat the test a lot of times you'll hear the buzzer once or twice, but those chances are slim for a loop executed only 5 times.

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