SparkFun Forums 

Where electronics enthusiasts find answers.

All things pertaining to wireless and RF links
By Danny
#163250
Hi all,

I'm about to venture on my first Arduino project. I'm just a beginner, but I think I can figure most things out... Except what combination of kit could 'solve my problem':

I want multiple battery-powered Arduinos (clients with sensors) to communicate with 1 single computer (server) - using a wireless connection. The server is to give commands to each individual Arduino, and each Arduino in response will prove a small data package in return (e.g. max 100 bytes) containing the sensor data. The server must be able to identify and address each Arduino individually.

Note however: The Arduinos will be in VERY CLOSE proximity from each other; for example: 4 to 15 centimeters!
The computer/server will be located 'a few meters' away (2 to 15 meters maximum).

Wi-Fi was my first choice (easy to ID & address & program?), but I'm afraid the relative 'extreme close-proximity' would cause too much interference when e.g. I have 5 or perhaps 20 Arduinos [literally] stacked on-top of each other! Is this true?

RF Radio is another wireless option and seriously cheaper as well!! But (I believe) lacks any form of ID, and the noise issue doesn't give me much confidence either..

So, my question is: What wireless solution would be best? And could you suggest any components/links that could do the job.

Any help will be much appreciated!

Danny
PS. I've been studying and reading for months so I'm dying to get started :dance: but I can't figure out what will or could work for my application :roll:
By jremington
#163262
Close proximity is not an issue, but a large number of connections can lead to problems. Xbee radios can be set up for star connections like you describe.

I don't know what "RF Radio" means, as RF = "Radio Frequency". But if you are referring to the extremely cheap and tiny 433 or 315 MHz modules, they offer only one communications channel (frequency) and most likely won't be suitable for your application.
By stevech
#163305
WiFi radio modules are overkill for telemetry; meaning higher cost, higher power consumption.
XBee Series 1 (S1), non-Zigbee), are simple, best fit.
Really cheap modules ($10 and less) can be made to work IF you are a wireless protocol guru and want a totally DIY programming task
By Mee_n_Mac
#163326
Danny wrote:I want multiple battery-powered Arduinos (clients with sensors) to communicate with 1 single computer (server) - using a wireless connection. The server is to give commands to each individual Arduino, and each Arduino in response will prove a small data package in return (e.g. max 100 bytes) containing the sensor data. The server must be able to identify and address each Arduino individually.
Given that each Arduino only transmits when it's been told to and is finished before the next one is commanded, I don't see a problem with overlapping transmissions. The "ID" of the Arduino being talked to could be part of the data transmitted by the server. All Arduinos hear the server broadcast, only the one being addressed answers with it's data packet.

Sounds like a job for one of the Nordic transceivers or a BT module, though at the distances mentioned I have to ask why not a wired connection ?

The OP might even look into replacing the Arduino + RF with a Wixel. I don't know if it'll be capable enough but ...
https://www.sparkfun.com/products/10665

Or a JeeNode, which is basically an Uno + and RF transceiver. I'm reasonably sure the onboard RF is "dumb" enough that a 1:N star topology is possible.
http://jeelabs.com/products/jeenode