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#1
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Random LED's
Does anyone know a good and simple way to have 4 LEDs blink in a random
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#2
Posted to alt.electronics
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Random LED's
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Hash: SHA1 My preference for a simple way would be to use a PIC microcontroller (pick your own preferred type here), and put something like a linear congruential generator on it (see Wikipedia - generating a number requires just a multiply and an add, if you let M be a power of 2). Once you generate an 8-bit output, use the upper 4 bits for your LEDs and throw away the lower 4 bits (the lower bits of a linear congruential generator have awful randomness). With an appropriate PIC, you can do this with literally nothing but the chip, a power supply, the LEDs, and the current-limiting resistors. Something like the 16F627A/16F628A/16F648A have a built-in oscillator and can run from 3 to 5.5 volts, so 3 AA batteries would power the whole system. You can also get the 16LF variant (instead of 16F) which can run down to 2V, so you could use only 2 batteries. I'm not familiar with the 10F series, but you can probably find a 10F series PIC that'll do the job just as well, and the 10F series have only 8 pins where the 16F648A has 18, so you'd use a lot less space. On the other hand, if you've never done any microcontroller work, it's a big job to get started. Chris Bill wrote: Does anyone know a good and simple way to have 4 LEDs blink in a random pattern -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (MingW32) Comment: GnuPT 2.7.2 Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEpV5U6ZGQ8LKA8nwRAsImAKCW85gdinFiqOYMKAY5Eh Wi79aFSQCg2hmQ lJudkoQiFCsaV/+3sVF81cQ= =7fyc -----END PGP SIGNATURE----- |
#3
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Random LED's
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Hash: SHA1 Unfortunately a schematic won't help. A PIC is a type of microcontroller, so you have to write code and then burn it into the chip. Writing the code requires a computer and programming knowledge, and burning it into the chip requires specialized hardware (a programmer). If you HAD these resources already available, a PIC would be both easy and cheap. If you have to acquire any of the above, it will be either difficult, expensive, or both, and I would suggest a different approach (at this point I stop being able to help you, since I don't know off-hand another way to solve your problem). Chris Bill wrote: [snip] I have never used a PIC, do you have a Schematic? -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (MingW32) Comment: GnuPT 2.7.2 Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEpY8W6ZGQ8LKA8nwRAvvLAJ4sq1XVWn3Q9Phcq7oI21 ljWLW7TwCfUxnR TSJ8ifdPee+umeAY0XWMxC4= =ErIR -----END PGP SIGNATURE----- |
#4
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Random LED's
On Fri, 30 Jun 2006 10:11:57 -0700, Bill wrote:
Does anyone know a good and simple way to have 4 LEDs blink in a random pattern --- Learning to cross-post might be a good start. -- John Fields Professional Circuit Designer |
#5
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Random LED's
"Chris Head" wrote in message news7dpg.85747$I61.65769@clgrps13... -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 My preference for a simple way would be to use a PIC microcontroller (pick your own preferred type here), and put something like a linear cripes, why have the guys spend hundreds of dollars in development tools for a single application. simple solution, get 4 blinking LEDs, wire them in parallel. after an hour they'll be random enough. |
#6
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Random LED's
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Hash: SHA1 Heh... because if you already HAVE the tools, because you do OTHER things with microcontrollers, then it's only a few dollars, and the solution is very small in terms of space taken up. I did say that if you don't already have the tools and knowledge this probably isn't a good idea. Chris Tater Schuld wrote: "Chris Head" wrote in message news7dpg.85747$I61.65769@clgrps13... -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 My preference for a simple way would be to use a PIC microcontroller (pick your own preferred type here), and put something like a linear cripes, why have the guys spend hundreds of dollars in development tools for a single application. simple solution, get 4 blinking LEDs, wire them in parallel. after an hour they'll be random enough. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.4 (MingW32) Comment: GnuPT 2.7.2 Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFErI8q6ZGQ8LKA8nwRAgM7AKCE/zcMkvmCTj76XMDPCk2cButDEACgnlMi rKrXvFCsQVp+S0/9UQv3rR4= =MWp9 -----END PGP SIGNATURE----- |
#7
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Random LED's
Bill wrote:
Does anyone know a good and simple way to have 4 LEDs blink in a random pattern I need some parameters. How random? Is the frequency of LED flashing to be low enough that it doesn't look like a blur to the eye? Probably the best simple method, if you don't have a uP development setup, is to have a 4-bit counter feeding the 4 LEDs (via current buffers probably), and a high frequency (1MHz?) clock feeding it via a gate so that it gets clocked for roughly 1mS and then sits with the 4-bit output reached for roughly 50mS, then counts again. So long as the counting time is varying slightly (a 555 timer might be variable enough by itself, but I'd suggest adding some simple radio output into the timing - ask me if you need a circuit). Mark. |
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