4017 Counter LEDs to stay on

Thread Starter

allenpitts

Joined Feb 26, 2011
109
Hello All About Circuits forum,

Using an Arduino to control a dozen 4017 - 555 circuits to sequence
320 LEDs. The problem is the 4017 turns on LED 1 then turns it off
and then turns on LED 2. The project wants to turn on LED 1 and
leave it on and then turn on LED 2 and leave LED 2 on, then
turn on LED 3 etc.

Maybe the 4017 won't do this but does any one know if it will
and if so how?

Thanks.

Allen in Dallas
 

dannyf

Joined Sep 13, 2015
2,197
Fairly easy: you just need to send a fast pulses from the mcu, like this:

'0', pause->1 pulse->'1', pause->2 pulses->'11', pause->5 pulses->'111', pause->7 pulses->'1111', pause....

If you send those pulses fast enough, no human eyes can tell the intermediate states.
 

Wendy

Joined Mar 24, 2008
21,938
320 LEDs? I assume each one is sequenced individually? Steering diodes / transistors can do it with 4017's, but there will be a large matrix involved.
 

Alec_t

Joined Sep 17, 2013
10,908
Maybe the 4017 won't do this but does any one know if it will
and if so how?
The 4017 enables only one output at a time. You could drive latches or OR gates with the 4017's outputs to get a staircase. Could you use LM3914 ICs in bar mode, instead of the 555/4017s?
 

Wendy

Joined Mar 24, 2008
21,938
Another possibility is to use a quad or 8 type D register that will clock over with a clock pulse. It would involve more ICs, but the logic is simple.

http://ecee.colorado.edu/~mcclurel/dm74ls374.pdf

http://www.nxp.com/documents/data_sheet/HEF4014B.pdf

http://www.redrok.com/CMOS_CD4021BC_8-StageStaticShiftRegister_Fairchild.pdf

There are others out there, this was just a sampling. I can draw up a simple type D approach if you are interested.

********

I think post #4 was talking a multiplex approach.

I am doing something whose basics might apply with multiplexing on

http://forum.allaboutcircuits.com/threads/topo-map-with-flashing-led.119557/page-7#post-958798

Post #100

I have a 256 LED display drawn up in the zip file. It could easily be expanded, and use a uC to sequence it.
 
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Thread Starter

allenpitts

Joined Feb 26, 2011
109
Hello AAC forum,

ISB123 I know this is not a schematic, more of pictorial but this the idea.


Colin55 Forgive me, I not sure how to 'drive the LEDs in a staircase'. Could you amplify?
I have hacked the Chaney 4431 and breadboarded the whole 555 to 4017 sequencer so
not afraid to build a PCB if need be.

This is 555 to 4017 operated by PIR sensor
Thanks.

Allen in Dallas
 

Bernard

Joined Aug 7, 2008
5,396
Welcome back, Allen. For a 320 LED bar graph I would suggest cascaded shift registers, for 320 steps & 8 bit SR's that is 40 SR's.
The 74HC164 is the longest SR that I can find and can direct drive LED's at 10 mA @ 6V VDD. Connect the serial inputs on first SR to high & a clock advances the high - stage by stage to the end. A clear signal clears all stages. A 555 might have enough drive for the clock. The SR's can be distributed along the line of LED's to keep leads short.
 
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Wendy

Joined Mar 24, 2008
21,938
If you used all 8 outputs that would be 4.9V drop, assuming a 0.7 V drop. The TS wants 360 outputs (an assumption on my part that I believe is the case). I like the base concept, but I suspect it is not workable. Steering diodes would have astronomical numbers associated, which probably kills that idea. So I'm back to the shift registers I referenced on post #7. Not sure if that meets the TS needs or not.

A 19x19 grid would be 361 LEDs, which would lend itself to the multiplexed CPU idea.
 

Wendy

Joined Mar 24, 2008
21,938
Again 360 LEDs, each sequentially turns on with 360 transistors. 360 Outputs would require 52 4017s cascaded to each other.
 

Wendy

Joined Mar 24, 2008
21,938
Just occurred to me, there is a sequential SCR circuit that does something similar, but the shift register seems like the best bet.

Waiting on TS input.
 

Colin55

Joined Aug 27, 2015
519
360 Outputs would require 52 4017s cascaded to each other.

Should be:

320 Outputs would require 32 x 4017s cascaded to each other.
 

Wendy

Joined Mar 24, 2008
21,938
360 Outputs would require 52 4017s cascaded to each other.

Should be:

320 Outputs would require 32 x 4017s cascaded to each other.
I had a math error, it is actually 45. Cascaded 4017 only allow 8 pins out per chip, except for the 1st chip, which is 9 output. I had plugged in 7 outputs.

Look at the data sheet.

http://www.ti.com/lit/ds/symlink/cd4017b.pdf

Page 3-55

temp.png

I use diode AND gates, which are quite convenient.

just need 3 ICs like AS1130 or MAX6953 or similar
Care to show us how? I'm interested. 320 LEDs is quite a few.
 
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Wendy

Joined Mar 24, 2008
21,938
Feeling a bit stupid, the TS did say he was using an Arduino, which puts it 9 pins of the 4017 usable (since there is no disable on the 4017.) 360 / 9 is 40.

Still unsure what the TS wants to do large scale. A giant 320 LED bar graoh?
 
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