I want to flash LED's in an interesting sequence and was wondering if
there some pre made device that could do this of if it could be made
with out too much difficulty. It's hard to describe the sequence so I
will use ascii art to show the sequence. O = on, X = off.

OOOXXXXXXX
XOOOXXXXXX
XXOOOXXXXX
XXXOOOXXXX
XXXXOOOXXX
XXXXXOOOXX
XXXXXXOOOX
XXXXXXXOOO

Then repeat or maybe reverse it and then repeat. This shows 10 LEDs,
but I may be using 15 or 20. I also have 2 different applications for
this. In one I each of the 15 to 20 positions will represent a single
high intensity LED. The other applications requires more intensity so
each position will be a group of 5 or 10 LEDs, so the circuit needs to
be handle enough current for than many LEDs.

--
Chris W

"They that can give up essential liberty
to obtain a little temporary safety
deserve neither liberty nor safety."
-- Benjamin Franklin, 1759 Historical Review of Pennsylvania

Hi Chris.

In my opinion, no single logic device will be able to handle it, or the
design effort isn't worth it (even using shift registers + initialization
logic around can lead to unexpected results and be very big).
The two obvious solutions would be :
- either an old EPROM (1 for 8 LED outputs) you program with the LED
sequence and you scan with a counter
- or a microcontroller with the program to output the sequence on its output
ports.

OK?

--

Thierry C.
Pour m'écrire, enlever les mots "spam" et "sucks" de mon adresse E-Mail

"Thierry C. (NOOS)" wrote:

Hi Chris.

In my opinion, no single logic device will be able to handle it, or the
design effort isn't worth it (even using shift registers + initialization
logic around can lead to unexpected results and be very big).
The two obvious solutions would be :
- either an old EPROM (1 for 8 LED outputs) you program with the LED
sequence and you scan with a counter
- or a microcontroller with the program to output the sequence on its output
ports.

OK?

The microcontroller sounds like the way to go to me. I haven't done any
electronics in years though. I am a programmer by profession now so I don't
think I will have a hard time learning to program the microcontroller but I have
now idea where to look to find one that is reasonably cheap and preferably
rather small. I'm thinking that I will need some external method of increasing
the current abilities for the version that lights 10 LEDs at once, is there a
pre packaged unit that would take signal to turn on a high current load? Kind
of like a solid state version of a relay board with a lot of inputs and outputs.




--
Chris W

"They that can give up essential liberty
to obtain a little temporary safety
deserve neither liberty nor safety."
-- Benjamin Franklin, 1759 Historical Review of Pennsylvania

Hello,

A bipolar transistor or FET or relay driver pack or led drivers etc. The
micro side is very easy
to program.

Geoff...

"Chris W" wrote in message
...
"Thierry C. (NOOS)" wrote:

Hi Chris.

In my opinion, no single logic device will be able to handle it, or the
design effort isn't worth it (even using shift registers +
initialization
logic around can lead to unexpected results and be very big).
The two obvious solutions would be :
- either an old EPROM (1 for 8 LED outputs) you program with the LED
sequence and you scan with a counter
- or a microcontroller with the program to output the sequence on its
output
ports.

OK?

The microcontroller sounds like the way to go to me. I haven't done any
electronics in years though. I am a programmer by profession now so I
don't
think I will have a hard time learning to program the microcontroller but
I have
now idea where to look to find one that is reasonably cheap and preferably
rather small. I'm thinking that I will need some external method of
increasing
the current abilities for the version that lights 10 LEDs at once, is
there a
pre packaged unit that would take signal to turn on a high current load?
Kind
of like a solid state version of a relay board with a lot of inputs and
outputs.




--
Chris W

"They that can give up essential liberty
to obtain a little temporary safety
deserve neither liberty nor safety."
-- Benjamin Franklin, 1759 Historical Review of Pennsylvania

The microcontroller sounds like the way to go to me. I haven't done any
electronics in years though. I am a programmer by profession now so I don't
think I will have a hard time learning to program the microcontroller but I have
now idea where to look to find one that is reasonably cheap and preferably
rather small.

Read m 'start with PICs page' at http://www.voti.nl/swp the name is
slightly misleading, it will also be usefull reading when you start
with another microcontroller.

I actually sell a kit that does 'interesting' LED sequencing, see
http://www.voti.nl/winkel/producten_1.html#K-KITT-1 , but not that I
mutiplex the LEDs (I drive 8 LEDs from 4 microcontroller pins), which
is probably to the way to go for you.

I'm thinking that I will need some external method of increasing
the current abilities for the version that lights 10 LEDs at once, is there a
pre packaged unit that would take signal to turn on a high current load? Kind
of like a solid state version of a relay board with a lot of inputs and outputs.

check ULN2803A (or the -7 version).


Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
PICmicro chips, programmers, consulting

A 74HC4017 decade counter has 10 outputs ,
one output 25mA high at a time ,
with max V+ of 6 VDC .
Thus each 74HC4017 output can light 3 series LED's .

Chris W wrote:

I want to flash LED's in an interesting sequence and was wondering if
there some pre made device that could do this of if it could be made
with out too much difficulty. It's hard to describe the sequence so I
will use ascii art to show the sequence. O = on, X = off.

OOOXXXXXXX
XOOOXXXXXX
XXOOOXXXXX
XXXOOOXXXX
XXXXOOOXXX
XXXXXOOOXX
XXXXXXOOOX
XXXXXXXOOO

Then repeat or maybe reverse it and then repeat. This shows 10 LEDs,
but I may be using 15 or 20.

maybe 12 series LED's fed with 10 74HC4017 outputs
and 10 NPN transistor switch's ?

--+--|--+--|--+--|--+--|--+--|--+--
| |
1of10 | |
4017 | /
OUT------+------------------|
25mA \
v
|
_____
___
_

Jim Davis wrote:

A 74HC4017 decade counter has 10 outputs ,
one output 25mA high at a time ,
with max V+ of 6 VDC .
Thus each 74HC4017 output can light 3 series LED's .

Chris W wrote:

I want to flash LED's in an interesting sequence
... ascii art to show the sequence. O = on, X = off.

OOOXXXXXXX
XOOOXXXXXX
XXOOOXXXXX
XXXOOOXXXX
XXXXOOOXXX
XXXXXOOOXX
XXXXXXOOOX
XXXXXXXOOO

Then repeat or maybe reverse it and then repeat. This shows 10 LEDs,
but I may be using 15 or 20.