Repeating circuit: 1, 2, 3, 1, 2, 3...

[Don Gilmore]

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

 

[Michael A. Terrell]

Don Gilmore wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

A 4017 decoded decade counter, connected to reset at three. If the
current is low enough, the LEDs can be driven directly.


http://www.datasheetcatalog.org/datasheet/philips/74HC4017.pdf

 

[John Fields]

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
<eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

---
View using a fixed-pitch font:

GND>------------------+----------+----------+
| | |
[LED] [LED] [LED]
|K |K |K
+-----+ | +-----+ | +-----+ |
+-|D1 Q1|-+--|D2 Q2|-+--|D3 Q3|-+
CLK>--------|-|CP _ | | _ | | |
VCC--+------|-|MR Q1|O-+ | Q2|O-+ | |
| | +-----+ | +-----+ | +-----+
| | HC175 | U1B | U1C
| | U1A [DIODE] [DIODE]
| | |A |A
+-[R]--+----------+----------+

--
JF

 

[John Fields]

On Sat, 08 Dec 2012 11:12:40 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

---
View using a fixed-pitch font:

Oops... ADD
\

---+----------+----------+
| | |
[LED] [LED] [LED]
|K |K |K
+-----+ | +-----+ | +-----+ |
+-|D1 Q1|-+--|D2 Q2|-+--|D3 Q3|-+
CLK>--------|-|CP _ | | _ | | |
VCC--+------|-|MR Q1|O-+ | Q2|O-+ | |
| | +-----+ | +-----+ | +-----+
| | HC175 | U1B | U1C
| | U1A [DIODE] [DIODE]
| | |A |A
+-[R]--+----------+----------+
--

JF

 

[John Fields]

On Sat, 8 Dec 2012 08:30:29 -0800 (PST), Don Gilmore
<eromlignod1@att.net> wrote:

A 4017 decoded decade counter, connected to reset at three. If the
current is low enough, the LEDs can be driven directly.
http://www.datasheetcatalog.org/datasheet/philips/74HC4017.pdf


I thought about a 4017, but didn't know that I could reset it at three. How is this done? Would I connect output 3 to the reset line? It is important that each output gets equal time...no pauses or skipped pulses.

Don

---
Connect pin 7 to pin 15.


--
JF

 

[Don Gilmore]

A 4017 decoded decade counter, connected to reset at three. If the
current is low enough, the LEDs can be driven directly.
http://www.datasheetcatalog.org/datasheet/philips/74HC4017.pdf

I thought about a 4017, but didn't know that I could reset it at three. How is this done? Would I connect output 3 to the reset line? It is important that each output gets equal time...no pauses or skipped pulses.

Don

 

[petrus bitbyter]

"Don Gilmore" <eromlignod1@att.net> schreef in bericht
news:eae0e822-2be2-440f-8b7a-2c85629ab8c2@googlegroups.com...

A 4017 decoded decade counter, connected to reset at three. If the
current is low enough, the LEDs can be driven directly.
http://www.datasheetcatalog.org/datasheet/philips/74HC4017.pdf


I thought about a 4017, but didn't know that I could reset it at three.
How is this done? Would I connect output 3 to the reset line? It is
important that each output gets equal time...no pauses or skipped pulses.

Don

Connect Q4 to MR and the counter resets immediately after the 3rd pulse. So
you will have a short pause in the ns area between pulse 3 and puls 1. You
may need to lengthen it somewhat if the Q4 does not fully reset the counter.
A diode and an RC will do that trick.

An alternative is a synchronous serial in parallel out shift register. "NOR"
the first and the second output and feed back to the serial input.

petrus bitbyter

 

[John Larkin]

On Sat, 08 Dec 2012 11:20:27 -0600, John Fields <jfields@austininstruments.com>
wrote:

On Sat, 08 Dec 2012 11:12:40 -0600, John Fields
jfields@austininstruments.com> wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

---
View using a fixed-pitch font:



Oops... ADD
\
GND>------------[R]---+----------+----------+
| | |
[LED] [LED] [LED]
|K |K |K
+-----+ | +-----+ | +-----+ |
+-|D1 Q1|-+--|D2 Q2|-+--|D3 Q3|-+
CLK>--------|-|CP _ | | _ | | |
VCC--+------|-|MR Q1|O-+ | Q2|O-+ | |
| | +-----+ | +-----+ | +-----+
| | HC175 | U1B | U1C
| | U1A [DIODE] [DIODE]
| | |A |A
+-[R]--+----------+----------+

LEDs are backwards.

You could almost use two of the LEDs as the diode AND.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

[whit3rd]

On Saturday, December 8, 2012 7:54:33 AM UTC-8, Don Gilmore wrote:

I'm an ME working on a small project where I'd like to do something ridiculously simple...
What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator...

I'm not sure why a function generator is useful, but if you have one,
set it to a ramp waveform (sawtooth) and use a bargraph display
chip (LM3914 or somesuch). One chip and the LEDs, and you're done.

Decoded counters (CD4017 in CMOS, SN74142 in TTL) are also available in a single
chip, you just need to worry about reset setup and hold times when you truncate
their sequence.

 

[John Fields]

On Sat, 08 Dec 2012 14:15:08 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 08 Dec 2012 11:20:27 -0600, John Fields <jfields@austininstruments.com
wrote:

On Sat, 08 Dec 2012 11:12:40 -0600, John Fields
jfields@austininstruments.com> wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

---
View using a fixed-pitch font:



Oops... ADD
\
GND>------------[R]---+----------+----------+
| | |
[LED] [LED] [LED]
|K |K |K
+-----+ | +-----+ | +-----+ |
+-|D1 Q1|-+--|D2 Q2|-+--|D3 Q3|-+
CLK>--------|-|CP _ | | _ | | |
VCC--+------|-|MR Q1|O-+ | Q2|O-+ | |
| | +-----+ | +-----+ | +-----+
| | HC175 | U1B | U1C
| | U1A [DIODE] [DIODE]
| | |A |A
+-[R]--+----------+----------+


LEDs are backwards.

---
True. Thanks.
---

You could almost use two of the LEDs as the diode AND.

---
Yup.

--
JF

 

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
<eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

 

[John Fields]

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.
--
JF

 

[John Fields]

On Sun, 09 Dec 2012 10:42:20 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.

---
Oops...

Got this confused with the make-a-bid thread.

Digi-Key onesies price for a 4017 is 60 cents and for the 175 with
diodes and pull-up, 72 cents.


--
JF

 

On Sun, 09 Dec 2012 10:42:20 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.

Yes, if cost is the overwhelming consideration. The 'axe can do duty
cycles from a microseconds to years without external timing caps and
the 4017 still needs a driving oscillator...

I've got a few 8 pin 'axes working my electric range - reads a pot,
creates a duty cycle based on the pot with a rep rate of ~10 seconds,
indicates heating with a tricolor led, red on, green off, magenta for
full power - a solid state relay does the heavy lifting, with a 2PST
mechanical safety relay to remove both sides of the line from the
element when it is off. Total cost was ~$20 and cheaper than the
bimetallic mechanical controls they replace.

 

[John Fields]

On Mon, 10 Dec 2012 09:08:46 -0500, default wrote:

On Sun, 09 Dec 2012 10:42:20 -0600, John Fields
jfields@austininstruments.com> wrote:

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.

Yes, if cost is the overwhelming consideration.

---
Well, there _is_ a little more to it than that.

For instance, the programming cable which if only used once would add
about USD16 to the cost of the project, and the time used to climb the
learning curve for a one-off would be pretty much wasted compared to
the time used to implement a simple hardware solution.


--
JF

 

[David Eather]

On Tue, 11 Dec 2012 00:55:20 +1000, John Fields
<jfields@austininstruments.com> wrote:

On Mon, 10 Dec 2012 09:08:46 -0500, default wrote:

On Sun, 09 Dec 2012 10:42:20 -0600, John Fields
jfields@austininstruments.com> wrote:

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something
ridiculously simple, yet I keep coming up with complex solutions.
There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three
discrete LED's--in a continuous circle using a square wave clock
input. If the LED's are numbered 1, 2 and 3, I want them to cycle
123123123123... The input would be the square wave from a function
generator and I'd like to control the speed of the LED's by the
frequency.

I keep coming up with complicated ideas like using a counter that
outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.

Yes, if cost is the overwhelming consideration.

---
Well, there _is_ a little more to it than that.

For instance, the programming cable which if only used once would add
about USD16 to the cost of the project, and the time used to climb the
learning curve for a one-off would be pretty much wasted compared to
the time used to implement a simple hardware solution.

John,

The 'programing cable' is three resistors to an RS232 port - most desktops
still have them OR a USB to serial adapter + three resistors. They give
you details on how to 'build' your own

The learning curve is so step that most grade school children are running
their first applications within 1 hr of being introduced to the system. My
first PICAXE was factoring numbers with 30 minutes (I couldn't think of
any thing else to do at the time) and I have heard of electronics people
up and running in under 20 minutes. For this type of thing it is
brilliant!

 

On Mon, 10 Dec 2012 08:55:20 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Mon, 10 Dec 2012 09:08:46 -0500, default wrote:

On Sun, 09 Dec 2012 10:42:20 -0600, John Fields
jfields@austininstruments.com> wrote:

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.

Yes, if cost is the overwhelming consideration.

---
Well, there _is_ a little more to it than that.

For instance, the programming cable which if only used once would add
about USD16 to the cost of the project, and the time used to climb the
learning curve for a one-off would be pretty much wasted compared to
the time used to implement a simple hardware solution.


Maybe. These things can be addictive so there's a good chance the

cable would be used again (and it's only serial port, two resistors
with a DB9 connector - the USB to RS 232 will add a few bucks if one's
computer lacks a serial port - then $3-$20 if you shop around - I have
some usb to serial TTL adapters from ebay that were $2.50)

The learning curve? I don't know. I had a smidgen of exposure to
basic programming years ago and had it up and flashing 4 leds in less
than an hour - The time went towards getting windoze to recognize the
usb adapter not learning the syntax .

Programming examples abound- flashing a led is the equivalent of
"hello world," when it comes to these things. Going from one led to
four or more is just a matter of duplicating a few lines of code (copy
and paste and change the pin numbers).

But I understand your point. Easier to do what one already
understands, and is comfortable with, than learn something new.

 

[Michael A. Terrell]

default wrote:

But I understand your point. Easier to do what one already
understands, and is comfortable with, than learn something new.

It can also be repaired in the field if it's damaged, but a
replacement micro will need the code burnt to it. I have an old RAM
tester that failed a few months after I bought it. It was now
discontinued, and the programmed IC was NLA. The employee who designed
it had quit, and all documentation was missing.

 

[John Fields]

On Tue, 11 Dec 2012 06:59:03 +1000, "David Eather" <eather@tpg.com.au>
wrote:

On Tue, 11 Dec 2012 00:55:20 +1000, John Fields
jfields@austininstruments.com> wrote:

On Mon, 10 Dec 2012 09:08:46 -0500, default wrote:

On Sun, 09 Dec 2012 10:42:20 -0600, John Fields
jfields@austininstruments.com> wrote:

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something
ridiculously simple, yet I keep coming up with complex solutions.
There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three
discrete LED's--in a continuous circle using a square wave clock
input. If the LED's are numbered 1, 2 and 3, I want them to cycle
123123123123... The input would be the square wave from a function
generator and I'd like to control the speed of the LED's by the
frequency.

I keep coming up with complicated ideas like using a counter that
outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.

Yes, if cost is the overwhelming consideration.

---
Well, there _is_ a little more to it than that.

For instance, the programming cable which if only used once would add
about USD16 to the cost of the project, and the time used to climb the
learning curve for a one-off would be pretty much wasted compared to
the time used to implement a simple hardware solution.



John,

The 'programing cable' is three resistors to an RS232 port - most desktops
still have them OR a USB to serial adapter + three resistors. They give
you details on how to 'build' your own

---
Well - even if you roll your own - there's the connector to plug into
the serial port, the cable connecting the resistors to the connector
on the other end of the cable, and the connector on the other end of
the cable.

All unneeded expenses for simple hardware solutions like the ones
Michael and I offered.
---

The learning curve is so step that most grade school children are running
their first applications within 1 hr of being introduced to the system. My
first PICAXE was factoring numbers with 30 minutes (I couldn't think of
any thing else to do at the time) and I have heard of electronics people
up and running in under 20 minutes. For this type of thing it is
brilliant!

---
You're preaching to the choir, David.

I've been doing analog and digital circuit design for over 50 years
and working with embedded systems since the 6502, so it's not like I'm
the neophyte you think you're addressing.

Unfortunately, many of the soothsayers laying hands on, and claiming
credit for miracles they have worked, don't realize that all they're
doing is driving the bus from point A to point B without actually
realizing how the miracle happened.
--
JF

 

[John Fields]

On Mon, 10 Dec 2012 16:56:22 -0500, default wrote:

On Mon, 10 Dec 2012 08:55:20 -0600, John Fields
jfields@austininstruments.com> wrote:

On Mon, 10 Dec 2012 09:08:46 -0500, default wrote:

On Sun, 09 Dec 2012 10:42:20 -0600, John Fields
jfields@austininstruments.com> wrote:

On Sun, 09 Dec 2012 08:35:41 -0500, default wrote:

On Sat, 8 Dec 2012 07:54:33 -0800 (PST), Don Gilmore
eromlignod1@att.net> wrote:

Guys:

I'm an ME working on a small project where I'd like to do something ridiculously simple, yet I keep coming up with complex solutions. There is probably a simple way to do this that I am missing.

What I'd like to do is cycle between three outputs--let's say three discrete LED's--in a continuous circle using a square wave clock input. If the LED's are numbered 1, 2 and 3, I want them to cycle 123123123123... The input would be the square wave from a function generator and I'd like to control the speed of the LED's by the frequency.

I keep coming up with complicated ideas like using a counter that outputs to a decoder. Surely there is an easier way?

Don
Kansas City

A single 8 pin Picaxe programmed to flash leds - no external parts
save current limiting for the leds or drivers for the leds if you need
watts of output. You can flash up to four with an 8 pin chip and do
any fancy flash sequence you can imagine.

Cost is ~$2-3

http://www.picaxe.com/Circuit-Creator/Light-and-LCD-Outputs/LED/

shows the basic code, you'd add two other outputs to the code

---
If the Picaxe price is 2-3$ (no PCB, LEDs, or current limiting
resistor), then the Digi-Key 100 piece price for the 4017 is 39 cents
each, and for the 175 with the diode and the pull-up, 36.7 cents.

Yes, if cost is the overwhelming consideration.

---
Well, there _is_ a little more to it than that.

For instance, the programming cable which if only used once would add
about USD16 to the cost of the project, and the time used to climb the
learning curve for a one-off would be pretty much wasted compared to
the time used to implement a simple hardware solution.


Maybe. These things can be addictive so there's a good chance the
cable would be used again (and it's only serial port, two resistors
with a DB9 connector - the USB to RS 232 will add a few bucks if one's
computer lacks a serial port - then $3-$20 if you shop around - I have
some usb to serial TTL adapters from ebay that were $2.50)

The learning curve? I don't know. I had a smidgen of exposure to
basic programming years ago and had it up and flashing 4 leds in less
than an hour - The time went towards getting windoze to recognize the
usb adapter not learning the syntax .

Programming examples abound- flashing a led is the equivalent of
"hello world," when it comes to these things. Going from one led to
four or more is just a matter of duplicating a few lines of code (copy
and paste and change the pin numbers).

---
Actually, no.

An index is also needed in order to keep track of what needs to be
flashed next and what needs to be done when the last LED in the string
is flashed.

I usually implement the index as a status register for the machine,
separate from the processor's own status register.
---

But I understand your point. Easier to do what one already
understands, and is comfortable with, than learn something new.

---
Then you misunderstand and, from your tone, perhaps on purpose.

--
JF