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Topic: [solved] Arduino to 4051 demux to optocoupler to HomeEasy remote problem (Read 1 time) previous topic - next topic


Hi all,

I'm trying to control a HomeEasy remote with the Arduino. I followed the instructions on this page

(Arduino pin --> optocoupler --> remote switch)

However instead of using 8 cables for the 4 on/off remote switches I used a 4051 demux so that I can save some pins on the arduino. I also did not use any LEDs.

If I go from an Arduino pin directly to the optocoupler and send a signal, the remote switches as it should.

If I measure resistance on the optocoupler on the side of the HomeEasy remote... and send something through the demux... I can see that the optocoupler is indeed switched...so the circuit is ok I guess... but the remote does not react at all... :(

Could this be a problem with too much resistance? What can I do to fix this? Sorry I'm a beginner on circuits.

The optocouplers I am using

The demuxer I am using

Thanks for your help

--- update


--- another update

Heureka! I found it. Turned out that when I had all outputs of the 4051 connected, I was sending always, even when LOW, LOW, LOW as input. But the remote didn't seem to like that and couldn't switch. When I unplugged the wire going from Y0 --> switch 1 OFF it worked!
That means currently I cannot turn off switch 1... but at the moment I only have 3 things to control anyway and I could extend the circuit  :)



The optocouplers I am using
The demuxer I am using

The schematic you are using?

Without seeing this it is hard to say.

What I can say is the 4051 is the wrong chip for output multiplexing because:-
1) It is analogue
2) It has no output latch so any signal is only momentary.


If I go from an Arduino pin directly to the optocoupler and send a signal, the remote switches as it should.

You are using a current-limiting resistor between the Arduino pin and the opto-coupler input I hope...  And yes without the circuit its impossible to know what's going on.
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