Max Current on Serial Pin TX - Uno

Using Arduino Project Guidance
1

Question at the end of post.

I wasn't really sure where to post this question, so, Mods, feel free to move it. Anyways, I have two Uno's and a future project in mind. I want to create a satellite dish of sorts for transmitting data across the room (mostly because I like how such dishes look). I have found that they operate primarily on light (much like every single RC operated things). I will be using a magnifying glass with an LED on the sending end - the LED will be at the magnifying glass' focal point.

The receiving end will have a 10K pull-down resistor and a phototransistor connecting the RX pin to VCC. That Arduino will print the data to an LCD screen. Think of it like using a remote to turn the TV to another channel.

My question is: can the Arduino provide enough current for the LED on the TX pin while the pin is configured for serial communication? I don't see why it shouldn't, but I don't want to take the chance.

2

free-bee:
can the Arduino provide enough current for the LED on the TX pin while the pin is configured for serial communication?

The driver used is the same regardless. You can safely source or sink 20mA of current. Up to 40mA before damage occurs.

3

Thanks for the reply. And I get to update this topic with some results.....

IT WORKS!!
I figured it would. But the reason I'm so excited here is that I tried forever to get it to. First, I wasn't getting anything to transfer out the TX line. I may be wrong here, but I think it had to do with the fact that the Arduino was still plugged into my laptop.

After I managed to get one AC adapter to power both (used really short jumpers), it failed to transfer data. I failed to get any stable readings on my DMM for a while. Turns out I was trying to ground the black lead to the only bus on my breadboard without a power connection. I also managed to find that I had to omit the pull-down resistor on the receiving end because the RX pin is holding it high. Which also means that I had to relocate the IR detector.

In the end, the RX pin was placed on one side of the detector, and the other side was directly grounded. But it left me in the spot that the data was going in inverted. Instead of "Test," I was getting "USt||". I tried to re-invert it with a 555 timer, but quickly realised why it wouldn't work. I ended up flipping the emitting diode around. And now it works.

So now, along with getting another AC adapter, I get to see how far away I can get data to transfer. I'll then use the magnifying glass to extend that distance. I then get to move to a parabolic mirror (or two).