random problem

[eggman]

Hello everyone,
I have a strange problem, I wrote a little program to control a VMUSIC2 MP3 player. It plays an MP3 with morse beeps that will then switch a lamp. The user can change the MP3 file without having to mess with the program.
After playing the file the player should wait between 0 and 45 minutes randomly before playing the morse code again.
All works okay but after a while the randomness disappears and it will always wait 45 minutes. Seems something wrong with the random command, maybe the seed? any help is appreciated. Here's the code:

' 12-05-09 morse code player, reads mp3 file to control lamp

@ device  pic12F683, INTRC_OSC_NOCLKOUT, wdt_off, pwrt_on, mclr_off, protect_off

include "modedefs.bas"
define  OSC 4
                           
OSCCON     = %01100000      ' Set to 4MHz	
CMCON0     = %00000111	    ' Analog comparators off 	
ANSEL      = %00000010	    ' Set AN1 as analog, rest digital 	    
TRISIO     = %00100010	                       
GPIO       = %00010000      ' GPIO.4 hoog voor serieel, start anders niet

relay       var GPIO.0
led         var GPIO.2

counter     var word
temp        var word
time        var word
audio       var byte 

pause 2000

loop:
     SerOut GPIO.4,T2400,["V3A",13]          ' play all songs
play_morse:
     toggle led
     adcin 1,audio
     if audio > 25 then                      ' test sound (more than 500 mV)
         high relay
     else
         low relay
     endif     
     SERIN2 GPIO.5,396,20,play_morse,[wait ("Stopped")]
     random temp
     time = temp/24                          ' between 0 and 45 seconds
     for counter = 1 to time
        pause 1000
        toggle led
     next counter
goto loop 
    
End

[tenaja]

If you read the section on Random, you will see that your output variable is also used as the seed. Try to use Random Time instead of Random Temp. That way your seed is changed after each use. In your code Temp is unnecessary anyway.

[eggman]

I'm not so sure about that, if I use time as my seed it will always be smaller then 2730, (time / 24) Will this not affect the output of the random generator?
i.e. does the seed need to be a 16 bit number or not?

[eggman]

Okay, I did a little test:
If I try this code:

loop:
     random temp
     toggle LED
     pause temp >> 8
goto loop

My LED flashes in a very nicely random way.

If I try this code:

loop:
     random temp
     temp = temp >> 8
     toggle LED
     pause temp
goto loop

Then it does not flash in a nicely random way.
So... the seed must not be modified.
But anyway this still does not explain why my morse code flasher doesn't work. Unfortunately I do not have the circuit at hand (it's in Paris now) so have to probably build a second one to really test.

[locko]

What about using your adcin 'audio' value as the seed - it seems like it should give you some randomness.

[eggman]

Hmm that's a good idea, will try, thanks