Distance limitation of Logic ICs / devices

Hi,

is it possible to join two logic ICs (TTL) in a distance of, let's say 50 meters?

One more thing, will it be possible to control my microcontroller circuit using a push button (wired) in a distance of 50meters or more?

What electronics solution should i take to make this situation possible. No wireless hardware, only button wired directly to the microcontroller

Hi

In fact it depends on the time of environment in which it works, the type of cable you use and the data rate you are transmitting, However TTL was not designed with long distance transmission in mind, the most suitable solution may be to employ serial communications (search for UART) which allows you to connect longer distances safely, the problem here is that you will probably need microcontrollers at both sides of your system.

There are many things to experiment though, there can be many solutions depending on your specific case.

About the push button, I think there is no problem, but better connect is a normally grounded to avoid noise interference.

good luck

Sal

emavil,
I recommend using a differential Line Driver/Line Receiver pair. Use a twisted pair connection, and terminate the line in a resistance of approximately 100 Ohms (the characteristic impedance of a twisted pair). Most Line recievers have built-in termination resistors that can be optionally connected. This scheme will give you good noise immunity.
.
Regarding the pushbutton. This will work, but I would recommend a spdt configuration with a 100 Ohm pullup resistor on each side or an active terminator on each side. Run three wires: the two switch poles and ground. On the receiving end connect the switch poles to the inputs of a cross coupled latch. This scheme will give you immunity from noise and from switch bounce.
Regards,
Kral

emavil,
The e-mail address referenced in your e-mail message on this topic appears to be invalid. My e-mail to you bounced.
Kral

You could complete a current loop from your switch and employ an optical isolator at the receiving end. This will work with very long cables and it will tolerate common mode voltages that would cause errors in or even destroy non-isolated transmission circuits.

If you need sharp, well defined signal edges at the receiving end then you can use a schmitt trigger at the opto-isolator's output to clean up the signal before passing it to the receiver logic circuitry.

So, apply a dc voltage across the series combination of opto-isolator, resistor and your remote switch. The switch sits all by itself as far away as you like from the other components, out at the end of a long cable.

Kral said:

emavil,
The e-mail address referenced in your e-mail message on this topic appears to be invalid. My e-mail to you bounced.
Kral

Click to expand...

Sorry kral, my emavil add is emavilengr@gmail.com

thanks

Added after 2 minutes:

lambtron said:

You could complete a current loop from your switch and employ an optical isolator at the receiving end. This will work with very long cables and it will tolerate common mode voltages that would cause errors in or even destroy non-isolated transmission circuits.

If you need sharp, well defined signal edges at the receiving end then you can use a schmitt trigger at the opto-isolator's output to clean up the signal before passing it to the receiver logic circuitry.

So, apply a dc voltage across the series combination of opto-isolator, resistor and your remote switch. The switch sits all by itself as far away as you like from the other components, out at the end of a long cable.

Click to expand...

Thanks a lot lambtron, that was a excellent suggestion in terms of safety and effecieny.

As long as your digital signal is not of high speed (frequency),
I think it should be fine.

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