I'm working on a project where I need to put an LED-illuminated switch about 50 feet from the Arduino. Can this be done reliably?
There have been several posts along these lines but I think the difference has been that the other posters were intending on shuttling data across the wire. I simply need to light up an LED and get a stable read from the button press.
I was intending to use use two digital ports (one for the LED and one to read the button using a pull down resistor) and 4-conductor phone wire.
Can a digital pin/button press be read reliably over 50 feet of phone wire (if appropriately debounced) or do I need to worry about interference? Would cat-5 be a better choice for wiring?
An earlier post suggested possibly using an analog port, pull up resistor and cap to smooth out any noise. Is this necessary?
Any hints/tips would greatly be appreciated.
Background:
This is for a Pinewood Derby solenoid activated start gate project. Basically, we currently have a "pickle" switch (a prescription drug bottle with an small incandescent light bulb and a momentary push button switch) that when pushed, activates a solenoid to flip the latch on the start gate (i.e, a physical spring-loaded latch/gate not electronic one). The pickle and solenoid circuit are currently connected via 50' of 18-2 speaker wire.
During each heat, a person would place the cars behind the start gate and, when ready, press and hold a button to indicate that the cars were ready. This would, in turn, cause the light in the pickle switch to light notifying the racer that the cars were ready and that the pickle switch was "armed".
The "process" issue that we have is that the person placing cars on the track would do so and enable the pickle switch before the timing computer was ready.
To solve this, I'm intending to use an Arduino with Cutedigi rs232 shield to interface with the timing computer. When the timing computer is ready it can raise DTR (rs232 pin 4) or RTS (pin 7) for a configurable period of time. I'm using the rs232 shield to detect this condition. (note: I may need to tie pin 4 and 2 together to fake the rs232 shield into thinking that data is available).
There will be a momentary push button at the starting line that can be pushed when the cars are ready to race. When both the timer and starting-line are ready I was going to illuminate the LED and wait for the racer to push the button to activate the solenoid.
Should be a fun project.