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jsolarski

need some coding help- 7 pins with 7 leds

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So lets start with the problem

7 pins, with 7 leds, I need to turn them on and off in a psudo-random order.

only one pin at a time should be on.

 

now i have been thinking about this and haven't come up with any way to do this.

its easy to go increment them one at a time, or shift bits in the P1OUT register, but it will not give me the effect i need.

 

 

 

any ideas?

 

 

thanks

-justin

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My white noise generator basically did the same thing, only to one pin.

 

http://blog.suspended-chord.info/?c=2

 

You could do something like...

 

 unsigned long int newr;
 unsigned char lobit;
 unsigned char b31, b29, b25, b24;
 unsigned char pin;

 // extract four chosen bits from the 32-bit register
 b31 = (reg & (1uL << 31)) >> 31;
 b29 = (reg & (1L << 29)) >> 29;
 b25 = (reg & (1L << 25)) >> 25;
 b24 = (reg & (1L << 24)) >> 24;

 // XOR the four bits together
 lobit = b31 ^ b29 ^ b25 ^ b24;

 // shift and incorporate new bit at bit position 0
 newr = (reg << 1) | lobit;

 // replace register with new value
 reg = newr;

 // choose a pin randomly
 pin = 1 << (rand()&7);

 // output value
 switch (reg & 1) { // work on the last bit of the register
   case 0:
     P1OUT |= pin;
     break;
   case 1:
     P1OUT &= ~pin;
     break;
 }

 

It works on the idea of a linear feedback shift register, which you can read about at Wikipedia: http://en.wikipedia.org/wiki/Linear_fee ... t_register

 

Hope this helps!

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