Why do people buy WiFi/Ethernet Shields when they could accomplish the same thing with a computer and two Arduinos (or 1 Standalone and 1 Arduino)?
I was thinking about setting up a system to monitor my plants, but the problem is that it's nowhere near a computer, so I came up with an idea. I would make a standalone Arduino (something very simple, with just the instrumentation, etc.) and attach an RF Transmitter (Like the one on Sparkfun).
Then, I would plug my Arduino into my computer (a hundred feet or so away), and attach an RF Receiver (like the matching one on Sparkfun).
I would then program the Transmitting one to check the values of the sensors like normal, then transmit the data to the waiting Receiving Arduino. The Receiver could send the data via Serial, and my computer (via a processing app or something) could post a tweet, email me, etc. with updates. There seem to be quite a few tutorials on transmitting and receiving with Arduinos with those products.
I think this would work, and it seems MUCH less expensive than those $40-60 USD WiFi/Ethernet shields.
The only problem I foresee is that the receiver uses the Arduino's RX pin, so that would interfere with sending info to the computer. Is there a way to set up another pin to receive the signal and decode it just like the RX pin? I believe there's a library somewhere, but I can't remember the name of it :).
Please comment/tell me if I'm mistaken somehow :P.
The only problem I foresee is that the receiver uses the Arduino's RX pin, so that would interfere with sending info to the computer.
Other people see other problems: if your neighbor opens her garage door with her remote at the exact moment your greenhouse monitor detects that the water pipe has burst, how does your "sending" Arduino know that it needs to resend the tweet that warns "Your garden is going hydroponic!"?
How does your Arduino find out that its latest status report disappeared into the ozone because the PC had auto-updated itself and rebooted?
If you make a PC an essential component of the system, you need to make sure it stays up and running through power outages, virus attacks, and other problems. That's a lot harder than just adding a small battery backup to a simple little Arduino.
Other people also have different goals and interests: some simply enjoy the challenge of squeezing full wireless networking capability into a small box you could have your dog wear as a backpack.
Regardless of your own criteria happen to be, it's an absolute certainty that there are lots of others whose criteria and priorities are completely different, and maybe even opposite.