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Topic: Log distance Signal (Read 391 times) previous topic - next topic

madguernseyboy

Jun 15, 2019, 07:26 pm Last Edit: Jun 15, 2019, 07:37 pm by madguernseyboy
If I have two Arduinos 50m apart and send a HIGH signal on one will it be received by the other even though it is so far away? Do i need a pull down resistor?

assume using 1mm house electric wire.



Thanks all.
Brendan

larryd

O/P to I/P requires no resistor.

You do know you will need a common ground return path between the two Arduinos?


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The last thing you did is where you should start looking.

jremington

You need two wires, signal and ground. For low data rates, 50m is no problem.

madguernseyboy

Thank you

so no need for the resistor.

I have a common ground so thats no problem either.

thanks
Brendan

larryd

BTW, using an opto coupler can prevent ground loop problems.

A 6N137/138 is a good choice.



No technical PMs.
The last thing you did is where you should start looking.

Wawa

#5
Jun 16, 2019, 08:49 am Last Edit: Jun 16, 2019, 08:50 am by Wawa
+1
There is the risk of phantom powering (if one is on and the other one is off).
I would use an opto coupler, as larryd suggested.
Use the opto at the receiving end (near input pin).

Opto emitter to ground, collector to pin, pull up enabled on input pin in setup().
 pinMode(optoPin, INPUT_PULLUP);
2-core wire from opto LED to other Arduino.

On the transmitter Arduino.
LED cathode wire there to ground, 1k resistor between output pin and LED anode wire.
Leo..

madguernseyboy

Hi all (thank you for the responses)

all arduinos would be powered from the same power supply so phantom powering shouldn't happen.

however just to ensure I got your description correct for others can you please check my schematic.


jremington

R1 may need to be lower, 220 Ohms or so. You will need INPUT_PULLUP or a 10K pullup resistor on D13.

larryd

If you use a 6N137 example:




No technical PMs.
The last thing you did is where you should start looking.

MarkT

For that long a run an optocoupler is wise, to prevent spikes destroying either Arduino when there is nearby lightning or heavy mains switching transients.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Wawa

all arduinos would be powered from the same power supply so phantom powering shouldn't happen.
Then forget about the opto coupler, and use shielded wires or twisted pairs for data and power. Cat-5 is cheap.
I hope you don't have any interfering sources near.
Leo..

can you please check my schematic.
The whole idea of an opto coupler is to have no ground link between devices, to prevent ground loops and interference.
Cut the short ground link under the opto in the diagram.
You now must have two separate supplies. A 5volt phone charger connected to the USB socket could do.
Leo..

NoraTheDoggo

O/P to I/P requires no resistor.

You do know you will need a common ground return path between the two Arduinos?



As long you don't use mains to power it, you can just shove a wire into the earth and connect it to the arduino ground. This will cause the arduinos to have a common ground without another wire.

I must ask you a question:
Have you considered a radio transmitter. You can get a sufficient pair for under 10 dollars.
I like cooking children and Arduinos
Is not the same as: I like cooking, children, and Arduinos
Grammar matters!

larryd

As long you don't use mains to power it, you can just shove a wire into the earth and connect it to the arduino ground. This will cause the arduinos to have a common ground without another wire."

OMG, but I live in the middle of the Sahara Desert :( .



No technical PMs.
The last thing you did is where you should start looking.

NoraTheDoggo

As long you don't use mains to power it, you can just shove a wire into the earth and connect it to the arduino ground. This will cause the arduinos to have a common ground without another wire."

OMG, but I live in the middle of the Sahara Desert :( .




You may be out of luck. The ground needs a little bit of moisture. Sorry.
I like cooking children and Arduinos
Is not the same as: I like cooking, children, and Arduinos
Grammar matters!

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