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[on:]

hello
i have a question
i am working on a weather station
i am using 15 sensor arduino's and one base station
all arduino's are fed by a solar panel and a battery
and the base station has a power adapter
i cant give the code so far becaus of a crash (have to rewrite most of it)
but now comes my question
i can read all arduino's if i am next to it
but i need a conection trough a wire (i love if it would be one)
the maximum distance would be 30 meters
and i need the arduino's to send a id code firsth
if somone can help me get those 2 i can do the rest myself

i was thinking of just one wire with a 10K to ground and a transistor pulsing 9V trough it

and the base station decivering the data

so only one way

[Reply #1 on:]

I would think about using an I2C bus.  Two wires instead of one, but it is a reliable, proven, robust technology with lots of products and tutorials. A Google search on "Arduino I2C" will produce everything you need. There is even an Arduino I2C library named "wire" in the reference or playground.

Good luck!

[Reply #2 on:]

i2c bus has a limet of few meters
i cant make buffers everywere becaus i want to see a yard and not only solar panals

[Reply #3 on:]

If you are going to string one wire you may as well string a double wire, like doorbell or speaker wire. If you use RS485 protocol that will be fairly resistant to noise.

http://www.gammon.com.au/forum/?id=11428

With just two wires you could "drop" each station off the same pair of wires, and have the master station send down a query, go into listening mode, and get a response back.

Another approach would be to go wireless, if each station has a solar panel. If not, you might want to have a second pair of wires to send the power down to each station.

[Reply #4 on:]

From another forum about extending I2C distance:

The length can be increased significantly by running at a lower clock frequency. One particular application - clocked at about 500Hz - had a bus length of about 100m (300ft).

I've run I2C approximately 50ft by using a low-capacitance cable and a slower clock.

Just sayin'

The other forum is at http://www.edaboard.com/thread80459.html

[Reply #5 on:]

i2c bus has a limet of few meters
i cant make buffers everywere becaus i want to see a yard and not only solar panals

If you get an I2C line extender (can't remember its exact name) I think you can get quite a bit of distance from it.

...

Here's one: P82B715 I2C-bus extender

Longer cables or low-cost, general-purpose wiring may be used to link I2C-bus based modules without degrading noise margins.