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Topic: cd4067 to read inputs... (Read 995 times) previous topic - next topic

patricka

Hello,

I'm fairly new to Arduino and electronics in general... so my appologies if the "vocabulary" I'm using in the following lines is not accurate...

I'm currently trying to use a cd4067 to read multiple inputs and send read data to the Arduino. The input signals that come from another board are 5V 3mA when "on". My simple question is: will this signal be high enough to be read/detected by the cd4067's inputs? By extension: can someone give me the signal range than can be read by the cd4067 (max voltage and current)?

Thank you very much.
Patrick

LarryD

Quote
The input signals that come from another board are 5V 3mA when "on".

What does that board do?

The o/p of the 4067 is going to an Arduino Uno digital i/p, correct?
Yes this would work if the 4067 is powered by a 5V supply.
The way you have it in your schematic isn't the same as how you have it wired up!

patricka

#2
Jul 16, 2013, 04:59 am Last Edit: Jul 16, 2013, 05:02 am by patricka Reason: 1
Thank you for your answer.

I will add a bit of context... I'm dealing with model railroads. I have several "detectors" on my layout to track train positions. Each detector has a led to indicate that a section of the layout is occupied by a train. I would like to remove that led and use this "signal" as an input on the cd4067. Then the Arduino will read the cd4067 to know which of the inputs is "on". In this way, I will be able to manage up to 16 "detectors" with a single cd4067 and a single Arduino. The characteristics 5V 3mA are given by the detector's manufacturer.

So, do you confirm that I do not need any other "element" between my detector and the cd4067 to be able to use that signal?


LarryD

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I have several "detectors"

You may not have to remove the LEDs.
Would you give us a link to these detectors?
The way you have it in your schematic isn't the same as how you have it wired up!

Grumpy_Mike

Quote
So, do you confirm that I do not need any other "element" between my detector and the cd4067 to be able to use that signal

Yes it looks like it. The CD4067 is an analogue multiplexer, this means that it will switch any voltage between ground and the power rail, in this case 5V. So if your sensor produces 5V or less it can go through this chip.
It is not even necessary to remove the LED, the voltage of about 2V across the LED will be transferred through the chip.

If however your sensor returns a 12V signal then you will have to cut this down to 5V or below before passing it to this chip. You do this with two resistors connected as a potential divider.

patricka

Thank you guys for your answers.

The occupancy detector board is from Digitrax, this is a classical BDL168 (for those who are familiar with DCC and railroad miniatures...). Here is a link to the documentation: http://www.digitrax.com/static/apps/products/detection-signaling/bdl168/documents/BDL168.pdf

At page 20, article 11.3, the information I gave earlier are discribed. When I answered you, I made a little mistake...: the leds are not soldered to the board. There is some output pins on which leds can be plugged to test occupancy, but in normal usage, there is no led... So I will use those output ports to create animations or maybe some kind of signal logic with an Arduino. As 16 output ports are available, I will use the cd4067 to be able to read them all if needed...

Hope this makes sense.
Patrick

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