Controlling RF dimmer with universal infrared remote

I have lots of software experience but almost no hardware experience, and I’ve decided to try my first Arduino project. I’ve done some upfront research on my own, but I still need some help

What I’m trying to do:

I currently have a dimmer switch for room lighting that uses an RF remote. I’d like to control it with a universal infrared remote. I’ve attached a very rough picture of my idea in the file diagram.png

What I have already:

Other things I think I need:

  • Temperature-controlled soldering iron
  • 4 Diodes

What I have done:

I found an article online that seems to apply to my situation:

I’ve carefully removed the circuit board inside the Pico remote from its case (see attachment pico.png), and I found some contacts under the five buttons. I assume that if I bridge these contacts, it will be like pressing the buttons.

Questions

How do I determine whether a button on the Pico is pulled down to GND or up to +3V? If I need to use the multimeter, what mode should be used, and what readings should I expect to see?

Assuming the button is pulled down to ground when closed (which I’m hoping), how do I safely determine which contacts (outer 4 or single inner) connect to ground, and which ones to an IC pin? Also, what type of diodes should I use? I’ve encountered several terms I don’t understand (“rectifier”, “switching”, “zener”, and “silicon”) and despite reading about them I’m still not sure which ones are appropriate.

diagram.png

pico.png

Interesting project and I hope you succeed!

Use multimeter's voltage mode, 20V is good enough.

If I am guessing it right, those five-exposed-pads are membrance switches, then it seems the center one is by itself.

Find the battery negative terminal, most likely labeled "-" on PCB. This usually is connected to ground plane. If you could not find the label, it seems that big round pad is for button battery, measure the polarity and trace the negative terminal.

So measure voltage between the center pad and the ground. If you get a positive reading (assuming your "-" of MM is connected to ground), it is most likely pull-up switch and the other four are connected to ground.

Take battery out, put your meter into connectivity mode and check to see if all the outer four pads are connected to others, I mean, other group of contacts. Do the same to the center pad. If all outer pads are connected to each other, check to see if they are connected to the ground plane.

If all switches are pulled-up type, pressing button will pull them down, then you can use a 2N3904 transistor as switch -- put a 1K resistor at base, connect collector to the center pad of five-pad-swich, and emitter to the ground. A positive signal at base will turn on the transistor and thus mimicing a button press.

I have not done hacks for "pulled-down" switch (ie, pressing button will connect to +3V), but a 2N3906 might do.

Good luck.

Thanks very much for your response, mjkzz.

I'm experimenting a bit right now and I'll let you know how it turns out.

Update: The project was a complete success. So much that I'll be doing a talk about it this week at a programmer's study group. I'll take some pictures and the code and do a quick write up and post it online soon, and then I'll link to it here for anyone who's curious.

I know it has been a long time, but if you are lurking, could you post the result?

Thanks