Help on choosing the right material

Hello

I have a project in my mind for a wild but I don’t know if it’s feasible with Arduino.

I would like to know what Arduino card I will have to buy to do so.

I want that an Arduino card can read normally close or open contact. If the state of those contacts change for a while ( like a contact switched from normally close to open during 30 second) the arduino detect it and send my an email to let me know that a certain contact is open or close.

I can get help about programming or I will fine solutions about that but can someone help me about hardware ?
What I have to buy ? :o

Thank for your help :slight_smile:

Well I know that I mint need ARDUINO GSM SHIELD 2...

Are those contacts connected to some electronics, or are we talking about an otherwise unconnected switch?

Hello,

Those contacts are connected to an electronic board and are drycontacts.

Lets said that the contact is N/C like a stop switch. Then someone push it for a wile then the contact is open for that time. I would like to be able to detect that and send it to myself by email.

Thank you

You have to measure what voltages are on those contacts before you wire it up to an Arduino in order to know how to design the interface circuit into the Arduino.

Find out which Arduino boards that the shield(s) that you want to use will fit. That will narrow the options down some. Probably an Uno or Mega.

It's simple to detect a [u]switch closure[/u]* and not much harder to time it if you can time it in [u]milliseconds[/u]. If you want to "get fancy" or if your program has to lots of other things and it can't constantly monitor the switch, you can use interrupts to "catch" the timing.

Of course, you'll need a "special" Arduino with a network connection. or an Ethernet, Wi-Fi, or GSM shield.

It should be feasible to send email but I don't know enough about the email protocol, so for me that would be the hardest part of this project. Maybe there's a library for that, but I don't know.

  • I generally use the Arduino's built-in pull-up resistors rather than an external pull-down like the digital read example.

Cool,

Thanks for your help !!!

I Can continue my project now.

I think that I will buy a starter-kit to play a bit... then later buy other board like Uno, Mega, Ethernet, Wi-Fi, or GSM shield.

Just have to be patient !

Grumpy_Mike:
You have to measure what voltages are on those contacts before you wire it up to an Arduino in order to know how to design the interface circuit into the Arduino.

Also possibly, signals if the contacts are multiplexed with other switches.

Hooking up to a contact already in a circuit board is tricky. You have to be careful to not blow up your Arduino (too high voltages can do this), but also to not have your Arduino appear to the existing circuit as closing the switch. Less likely to happen, but still possible.

Detecting a button state change for a period of time is easy to accomplish.

If you want to use a WiFi connection, you may be better off with an ESP8266 based board, such as NodeMCU or WeMOS D1. A pretty powerful microprocessor with WiFi built in already. Much easier to work with than Arduino + WiFi shield (which may be built around an ESP8266 anyway).