Demuxing, what am I doing wrong?

D

Daniel Pitts

Guest
Hello everyone,

Please forgive me if this isn't the correct group for this kind of question.

I've just started trying to get into digital electronics as a hobby. I'm
a long time software engineer, so I've got the logician skills (I hope).
I've been playing around with an Arduino board, and I'm trying to design
a LED matrix display just as a proof of concept. I've gotten a few
simple circuits to work, and now I'm moving on to something more
complicated.

I've bought an 74HCT138 IC, and tried hooking it up to switch between 5
different "rows" or LEDS. For my first experiment, I hooked up the pins
8(gnd) and 6(E3) to gnd on my Arduino board, and then pins 16(Vcc), 4
(E1 high), and 5 (E2 high) to the +5 of my Arduino. I then connected
pins 11,12,13,14,15 to some LEDs with resisters.

I tried hooking up pin 1,2,3 (A0-A2) to a few output pins on the
Arduino, and just wrote a basic counter to try to cycle through the
various values. My counter changes every 500ms, and the voltages on the
input-pins match my expectations. The problem is that it doesn't appear
to be decoding.

All of the LEDs are on, an none of them turn off ever. I realize of
course, that I have the LEDS hooks up the opposite to how I want them,
but even so I should see exactly one in the opposite state, and yet they
are all the same.


Thanks,
Daniel.

P.S. If there is a more appropriate newsgroup, please let me know.
 
On 5/19/12 5:29 PM, Daniel Pitts wrote:
Hello everyone,

Please forgive me if this isn't the correct group for this kind of
question.

I've just started trying to get into digital electronics as a hobby. I'm
a long time software engineer, so I've got the logician skills (I hope).
I've been playing around with an Arduino board, and I'm trying to design
a LED matrix display just as a proof of concept. I've gotten a few
simple circuits to work, and now I'm moving on to something more
complicated.

I've bought an 74HCT138 IC, and tried hooking it up to switch between 5
different "rows" or LEDS. For my first experiment, I hooked up the pins
8(gnd) and 6(E3) to gnd on my Arduino board, and then pins 16(Vcc), 4
(E1 high), and 5 (E2 high) to the +5 of my Arduino. I then connected
pins 11,12,13,14,15 to some LEDs with resisters.
I flipped the concept of the three enable pins. I had high's where I
Click to expand...
should have had lows and visa-verse. It is now working as expected. Oops.
 
On Sat, 19 May 2012 20:08:31 -0700, Daniel Pitts
<newsgroup.nospam@virtualinfinity.net> wrote:

On 5/19/12 5:29 PM, Daniel Pitts wrote:
Hello everyone,

Please forgive me if this isn't the correct group for this kind of
question.

I've just started trying to get into digital electronics as a hobby. I'm
a long time software engineer, so I've got the logician skills (I hope).
I've been playing around with an Arduino board, and I'm trying to design
a LED matrix display just as a proof of concept. I've gotten a few
simple circuits to work, and now I'm moving on to something more
complicated.

I've bought an 74HCT138 IC, and tried hooking it up to switch between 5
different "rows" or LEDS. For my first experiment, I hooked up the pins
8(gnd) and 6(E3) to gnd on my Arduino board, and then pins 16(Vcc), 4
(E1 high), and 5 (E2 high) to the +5 of my Arduino. I then connected
pins 11,12,13,14,15 to some LEDs with resisters.
I flipped the concept of the three enable pins. I had high's where I
should have had lows and visa-verse. It is now working as expected. Oops.
Click to expand...
Pretty much everybody will admit to having gotten an "active high"
versus "active low" backwards at least once. The rest are lying. ;-)

Also, meta-answers and suggestions: Yes, this is the correct group.

Pick up a copy of LTSpice http://www.linear.com/designtools/software/.
It's free and has become the de facto way of sharing circuit questions
(e.g., "I've got this crazy oscillator and ...") since the file format
is ASCII and can be posted as text. And, it's a pretty good SPICE
simulator.

There's also Andy's ASCII-Circuit http://www.tech-chat.de/aacircuit.html
to post small circuit snippets

--
Rich Webb Norfolk, VA
 
On 5/20/12 6:39 AM, Rich Webb wrote:
On Sat, 19 May 2012 20:08:31 -0700, Daniel Pitts
newsgroup.nospam@virtualinfinity.net> wrote:

On 5/19/12 5:29 PM, Daniel Pitts wrote:
Hello everyone,

Please forgive me if this isn't the correct group for this kind of
question.

I've just started trying to get into digital electronics as a hobby. I'm
a long time software engineer, so I've got the logician skills (I hope).
I've been playing around with an Arduino board, and I'm trying to design
a LED matrix display just as a proof of concept. I've gotten a few
simple circuits to work, and now I'm moving on to something more
complicated.

I've bought an 74HCT138 IC, and tried hooking it up to switch between 5
different "rows" or LEDS. For my first experiment, I hooked up the pins
8(gnd) and 6(E3) to gnd on my Arduino board, and then pins 16(Vcc), 4
(E1 high), and 5 (E2 high) to the +5 of my Arduino. I then connected
pins 11,12,13,14,15 to some LEDs with resisters.
I flipped the concept of the three enable pins. I had high's where I
should have had lows and visa-verse. It is now working as expected. Oops.

Pretty much everybody will admit to having gotten an "active high"
versus "active low" backwards at least once. The rest are lying. ;-)
Yep, thanks for the validation ;-)
Click to expand...

Also, meta-answers and suggestions: Yes, this is the correct group.
Sweet. You might see me around here some more then, now that I'm
Click to expand...
experimenting.

Pick up a copy of LTSpice http://www.linear.com/designtools/software/.
It's free and has become the de facto way of sharing circuit questions
(e.g., "I've got this crazy oscillator and ...") since the file format
is ASCII and can be posted as text. And, it's a pretty good SPICE
simulator.
Sounds good, but I have a Mac as my primary machine, any suggestions for
Click to expand...
similar software there?

There's also Andy's ASCII-Circuit http://www.tech-chat.de/aacircuit.html
to post small circuit snippets
Another useful looking software that runs only on Windows ;-)
Click to expand...

Thanks,
Daniel.
 
On Sun, 20 May 2012 08:55:27 -0700, Daniel Pitts
<newsgroup.nospam@virtualinfinity.net> wrote:

On 5/20/12 6:39 AM, Rich Webb wrote:
On Sat, 19 May 2012 20:08:31 -0700, Daniel Pitts
newsgroup.nospam@virtualinfinity.net> wrote:

On 5/19/12 5:29 PM, Daniel Pitts wrote:
Hello everyone,

Please forgive me if this isn't the correct group for this kind of
question.

I've just started trying to get into digital electronics as a hobby. I'm
a long time software engineer, so I've got the logician skills (I hope).
I've been playing around with an Arduino board, and I'm trying to design
a LED matrix display just as a proof of concept. I've gotten a few
simple circuits to work, and now I'm moving on to something more
complicated.

I've bought an 74HCT138 IC, and tried hooking it up to switch between 5
different "rows" or LEDS. For my first experiment, I hooked up the pins
8(gnd) and 6(E3) to gnd on my Arduino board, and then pins 16(Vcc), 4
(E1 high), and 5 (E2 high) to the +5 of my Arduino. I then connected
pins 11,12,13,14,15 to some LEDs with resisters.
I flipped the concept of the three enable pins. I had high's where I
should have had lows and visa-verse. It is now working as expected. Oops.

Pretty much everybody will admit to having gotten an "active high"
versus "active low" backwards at least once. The rest are lying. ;-)
Yep, thanks for the validation ;-)


Also, meta-answers and suggestions: Yes, this is the correct group.
Sweet. You might see me around here some more then, now that I'm
experimenting.

Pick up a copy of LTSpice http://www.linear.com/designtools/software/.
It's free and has become the de facto way of sharing circuit questions
(e.g., "I've got this crazy oscillator and ...") since the file format
is ASCII and can be posted as text. And, it's a pretty good SPICE
simulator.
Sounds good, but I have a Mac as my primary machine, any suggestions for
similar software there?

There's also Andy's ASCII-Circuit http://www.tech-chat.de/aacircuit.html
to post small circuit snippets
Another useful looking software that runs only on Windows ;-)
Click to expand...
There seems to be a free Mac SPICE over at http://www.macspice.com/.

For general schematic capture, try Kicad, which is FOSS.

Also, WINE?

--
Rich Webb Norfolk, VA
 
On Sun, 20 May 2012 08:55:27 -0700
Daniel Pitts <newsgroup.nospam@virtualinfinity.net> wrote:

<snip>
There's also Andy's ASCII-Circuit
http://www.tech-chat.de/aacircuit.html to post small circuit
snippets
Another useful looking software that runs only on Windows ;-)

Thanks,
Daniel.
Click to expand...
Daniel, there are some Spice programs that have been ported to other
systems. You can probably Google around for something that will run on
a Mac.

I use Linux and there are several decent Spice programs that work for
it. To my understanding, the Mac OS-X system is a flavor of Unix/Linux,
and many ports to one will run on the other. You should be able to
find something you can use.

--
 
On Sun, 20 May 2012 12:48:57 -0400
Rich Webb <bbew.ar@mapson.nozirev.ten> wrote:

<snip>

There seems to be a free Mac SPICE over at http://www.macspice.com/.

For general schematic capture, try Kicad, which is FOSS.

Also, WINE?
Click to expand...
WINE is free, so it's worth a shot; but I've never had much luck with
it when trying to run graphics-intensive programs.

--
 
On 5/20/12 2:35 PM, chiron613@taearaneawas.com wrote:
On Sun, 20 May 2012 08:55:27 -0700
Daniel Pitts<newsgroup.nospam@virtualinfinity.net> wrote:

snip

There's also Andy's ASCII-Circuit
http://www.tech-chat.de/aacircuit.html to post small circuit
snippets
Another useful looking software that runs only on Windows ;-)

Thanks,
Daniel.

Daniel, there are some Spice programs that have been ported to other
systems. You can probably Google around for something that will run on
a Mac.

I use Linux and there are several decent Spice programs that work for
it. To my understanding, the Mac OS-X system is a flavor of Unix/Linux,
and many ports to one will run on the other. You should be able to
find something you can use.

Use, Mac OS-X is built off of BSD, so a lot of Unix based programs will
Click to expand...
run on it, though not with the native UI. Which is fine for this kind of
thing. Thanks for the hint.
 
In article <Qt8ur.29502$_l.420@newsfe15.iad>,
Daniel Pitts <newsgroup.nospam@virtualinfinity.net> wrote:

On 5/20/12 6:39 AM, Rich Webb wrote:
On Sat, 19 May 2012 20:08:31 -0700, Daniel Pitts
newsgroup.nospam@virtualinfinity.net> wrote:

On 5/19/12 5:29 PM, Daniel Pitts wrote:
Pick up a copy of LTSpice http://www.linear.com/designtools/software/.
It's free and has become the de facto way of sharing circuit questions
(e.g., "I've got this crazy oscillator and ...") since the file format
is ASCII and can be posted as text. And, it's a pretty good SPICE
simulator.
Sounds good, but I have a Mac as my primary machine, any suggestions for
similar software there?
Click to expand...
Get a copy of Wine Bottler, it's a foolproof way of installing Wine on
OSX. Then LTSpice will run under Wine with no problems.

http://www.macupdate.com/app/mac/33367/winebottler
 
On 2012-05-20, Daniel Pitts <newsgroup.nospam@virtualinfinity.net> wrote:
Pick up a copy of LTSpice http://www.linear.com/designtools/software/.
It's free and has become the de facto way of sharing circuit questions
(e.g., "I've got this crazy oscillator and ...") since the file format
is ASCII and can be posted as text. And, it's a pretty good SPICE
simulator.
Sounds good, but I have a Mac as my primary machine, any suggestions for
similar software there?
Click to expand...
wine, and ltspice.

There's also Andy's ASCII-Circuit http://www.tech-chat.de/aacircuit.html
to post small circuit snippets
Another useful looking software that runs only on Windows ;-)
Click to expand...
I just use a text editor, for really ambitious projects I might use
aewan, dunno what there is for mac.

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---
 
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