What distance can LCD be separated from Arduino?

Hello,
Does anyone have any experience of running a standard LCD module at, say, 1 metre from the Arduino? I am putting together a thermostat where the power/Arduino/relays etc will be in a power base which will be sited away from the display and any up/down/set buttons. If feasible, any recommendations for cable? twisted? shielded? ribbon? This to avoid climbing over an electrically heated water tank to see the readings or set the temperatures. Wireless?
Thanks

had no trouble with an I2C - LCD on 75 centimeter. parallel LCD I never used longer than ~20 centimeter. rs232 LCD max 150 centimeter - 19200 baud.

Any distance will work.... but you might have to slow down the data transmission rate.

1m isn't really very far, electronically speaking.

fungus: Any distance will work.... but you might have to slow down the data transmission rate.

1m isn't really very far, electronically speaking.

Well, at some point, voltage drop will come into play and no matter how slow you transition the signals, it won't work anymore. As wires get longer you also run the rist of crosstalk or inductance creating noise on the lines.

--- bill

Noise pickup, reflections and so forth will start to dog logic signals sent over too long a cable, I wouldn't recommend siting any digital logic component remotely unless using a bus that has well characterised behaviour, such as OneWire or TTL RS232, USB, ethernet, RS485. You may get away with it, but you could be sailing close to the wind (if you have an oscilloscope you can see how well the signals are holding out).

I would be assuming you are going to use an I2C "backpack" on the display, so you only need four wires - two power and two signal lines. Voltage drop will not be a concern at all, but you may have to modify some code to slow down the I2C protocol - which is perfectly OK as it will operate quite happily at any lower speed.

Shielding will probably not be necessary, and shielded cable has a much higher capacitance which would again require slower communication.

bperrybap:

fungus:
1m isn’t really very far, electronically speaking.

Well, at some point, voltage drop will come into play and no matter how slow
you transition the signals, it won’t work anymore.
As wires get longer you also run the rist of crosstalk or inductance creating
noise on the lines.

Sure, but 1m isn’t really very far, electronically speaking and voltage losses will be very small at milliamp currents.

Hello everyone, Thanks for all the replies. I will give it a go and report back - at least no "won't works". I am still very new to all this, but enjoying the challenges. Setting up commercial programmable room thermostats and the like are always a challenge if sited 2 feet from the floor. I like to get buttons bit away from the guts of it on as long a lead as possible. Transmission speed will not be a problem with what is going to be a very slowly changing signal. I used to work with very high impedance sources (pH electrodes) where any movement of the cables caused problems. Answer - put the amplifier on the top of the electrode and the cable and length becomes a non-issue. regards

fungus:

bperrybap:

fungus: 1m isn't really very far, electronically speaking.

Well, at some point, voltage drop will come into play and no matter how slow you transition the signals, it won't work anymore. As wires get longer you also run the rist of crosstalk or inductance creating noise on the lines.

Sure, but 1m isn't really very far, electronically speaking and voltage losses will be very small at milliamp currents.

I know that 1m isn't very far. However what you actually said was:

Any distance will work.... but you might have to slow down the data transmission rate.

And it is the Any distance will work that you previously said and left off my quote above, that I was referring to. i..e if you tried say 100m, 500m or 1km it wouldn't work. Yes I know that isn't what the OP said and wouldn't be doing, but you said "Any distance" which to me is indicating a false sense of reliability.

But even with small distances you can have serious issues. For example, without proper decoupling and/or filtering you can have ground bounce issues using TTL signals and switching loads with wires as short a 10-12cm.

I'd be more likely to do it the way home HVAC thermostats work. The processor, buttons, and display with the temp sensor are together. The power supplied by remote supply (like 24 volts) and the heavy lifting relays are also remote. The thermostat gets power from the remote supply and can turn on power signals to power the remote relays. That way the transmission lines are simple power lines with higher than TTL type voltages with no data communications.

tigger, it would be nice to know a bit more about what you are doing and what electrical components you need to interface to. This would help in proposing solutions.

-- bill

bperrybap:

Any distance will work.... but you might have to slow down the data transmission rate.

And it is the Any distance will work that you previously said and left off my quote above, that I was referring to. i..e if you tried say 100m, 500m or 1km it wouldn't work.

It all depends on your wire.

If you use 1 AWG wire then the resistance is only 0.0004 ohms per meter. You could go a few km (miles) with that, no problem.

http://www.daycounter.com/Calculators/AWG.phtml

At some point the cost of the copper needed to make it work will become prohibitive. That's the real limiting factor for the original poster, not the distance.

fungus:
It all depends on your wire.

If you use 1 AWG wire then the resistance is only 0.0004 ohms per meter. You could go a few km (miles) with that, no problem.

That only applies to DC. If you are sending a signal down a set of wires you need to
understand how signals propagate, characteristic impedance, cable capacitance, inductance,
the skin effect, noise coupling, RFI, ground-mismatch…

If you have high speed logic signals you can’t just assume you can put them down long
cables and have everything work.

MarkT: That only applies to DC. If you are sending a signal down a set of wires you need to understand how signals propagate, characteristic impedance, cable capacitance, inductance, the skin effect, noise coupling, RFI, ground-mismatch...

If you have high speed logic signals you can't just assume you can put them down long cables and have everything work.

I'm sure I said ".... but you might have to slow down the data transmission rate".

And how does that stop RFI and noise pickup exactly?