Getting external data to the Arduino

Question

I have a new Uno R3, it's pretty cool and I've enjoyed playing with it.

Now I want to build a couple of things:

1) a market price LCD tracker.

2) a servo motor type thing to open my electric gate.

Both of these either require input from an external website or some kind of message to initiate the action on the Arduino.

How do people generally get data onto the Arduino, I found a lot of conflicting information online.

Does this thing have Wifi or Bluetooth??

I got this pack, it doesn't seem to have either Wifi or Bluetooth, if not how do ppl generally get data onto the Arduino?

I have a raspberry pi spare, can I just use that, sending data from pins?

Answer 1

How do people generally get data onto the Arduino, I found a lot of conflicting information online.

There are various ways depending on what the data is and how you access it.

Does this thing have Wifi or Bluetooth??

Not unless you add WiFi or Bluetooth to it, no.

I have a raspberry pi spare, can I just use that, sending data from pins?

Yes, there are ways.

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How you go about getting data on to an Arduino depends very much on how the data is accessed. It is possible to add a WiFi interface to an Arduino, either through an official WiFi shield or through adding something like an ESP8266 on a breakout board (ESP-01 is popular) although interacting with the ESP8266 can be tricky.

You can do the same with Bluetooth or any number of other wireless protocols.

The simplest method of getting data to the Arduino, though, is through the USB serial port. Since you have a Raspberry Pi available the most logical option would be to plug the Arduino directly into the Pi's USB port. The Pi can then communicate through /dev/ttyACM0 (or /dev/ttyUSB0 for some clones) and the Arduino receive the data through the Serial object. Exactly how you arrange all that is entirely up to you.

Answer 2

It depends on the kind of data and where it will be coming from. Trigging your gate really only needs a signal to start moving, though a directional signal would be better ("Open" or "Close"). What is the source of that signal and far from from the gate will it originate?

If you're willing to press a button on the gate, it's a simple matter of sensing the button with one of the Arduino's pins. If you want to operate it from your phone from right in front of the gate, a Bluetooth module on the Arduino could pick up the phone's signal. If you also need to operate it from further away - more than 5-10 meters, a pair of RF modules with stick-antennas like the ones on a WiFi router, might get you 100m.

For the market-price tracker, your data is probably coming from the internet, in which case you'd need either an ethernet module or a WiFi module that would link it to the internet through your local network. Or if this device has to be portable, you could use a cellular module to link it to the internet through the cellular network. This latter is usually expensive - the price of adding an additional line to your cellular plan, for instance.