I am new to to Arduino. I purchased a Mega 2560 board and an ethernet shield today and needed some help getting started.
I currently have some buttons on my desk that control a number of things: Imgur: The magic of the Internet (I have since added more buttons so I have around 30-40 buttons in total now.)
The buttons are connected to wires that are either soldered directly to the circuit boards of my monitors, volume buttons on my TV and hifi, pc power switch etc or either are soldered onto remote controls where the sensor is pointing at the receiver. They are all simple push buttons which i assume have very low voltage and ampage passing through them.
What I eventually want to do it create an android app and have a tablet to replace the buttons. At first I thought I could connect the wires directly to the Arduino board and just write some code that will sort of join the wires for a second and "press" the button. However after some reading I don't think its possible this way and I assume I have to get a breadboard and use relays and transistors etc. Where do I start and what else will I need to purchase to get going? Can I buy some Relays/Transistors that will support up to a certain voltage/ampage so I dont have to measure each circuit. Do I then connect the outputs on the breadboard to the relays so toggling the output for a second will "press" the button for a second?
Also how do I get the Android app side of things working? The Arduino will be connected to an ethernet cable and I plan to use the tablet to control the buttons over the internet. Will I have to write the code in the Android App itself to control the Arduino? Or will I have to write the code for the Arduino on my PC and upload it to the Arduino and then just pass certain commands from the Android app to the Arduino over the internet for certain buttons to be pressed?
You have wired together a lot of things. Good for you. First, I would measure the voltage across each button and write them down. Arduino can use a digital pin to "press" these buttons directly if their voltage across is 5V or less. There might be a common among all your buttons. If possible, identify this pin. There are pull-up and pull-down resistors with buttons. You need to find out which.
If you don't want to be a lazy idiot that risks damaging things, the first step is to take a multimeter and measure the voltage and current of every button you want to control.
You say you have wired to remote control buttons, is it possible to just give the Arduino an IR LED and have it send the codes itself instead of that roundabout wiring way? Not enough detail about your devices, so just something to consider.
But if you are lazy, I think you'd probably be okay with just replacing all buttons with an optocoupler, and then really all you're doing codewise is turning on an LED to 'push' each button.
The only component that "really has a plain switch" is a relay. So the easy thing is to use relays.
The easy way to use relays is to use opto-isolated relay boards, which are made by the thousands (maybe millions).. You can find them on Ebay, Sparkfun, Adafruit etc etc.
INTP:
Relay for a TV volume button? That is daft and hardly the 'easy thing' to do.
If the device he is attempting to connect to already has buttons for the controlling the volume, say
Button 1 : increment volume X db
Button 2 : decrement volume X db
then why not substitute relays. At least that would be one to one.
However, I would certainly tend to keep the original TV remote control unless I was really determined to get everything functioning from my own console.
Because a relay module that itself uses a transistor and possibly also an optocoupler to replace a microswitch when just that transistor or that opto would work perfectly well is dumb and essentially a Rube Goldberg. Times 40.
