arduinojavaledprocessingpython
I have a question regarding the programming of printing text on the screen after an LED lights up on a breadboard. Should we plug in the LED into the Arduino board or a regular breadboard? How do I get the Arduino to recognize that the LED has lit up? I am doing a physical game where if you touch the wire with a wand, a buzzer and a LED lights up, which is currently connected as a parallel circuit.
Thank you very much in advance!
To know how things are connected on the Arduino itself you have to take a look at the schematic. This one is the Arduino Uno's. At the bottom right you can see how the board's I/Os are connected to the microcontroller:
So following the line from pin 13 you go to PB5 of the microcontroller. That means bit 5 of port B. If you set that pin to output and make it high you're supplying 5 V to the LED circuit. The series resistor will limit the current to about 5 mA, which is an OK value for the microcontroller.
So, since the 5 V comes from the Arduino's I/O pin the 5 V wire on the breadboard isn't needed.
You could power a small 24V relay via a bridge rectifier and small smoothing capacitor. Use the relay contact outputs to feed the appropriate dc voltage to the arduino. Here: -
The 26V ac when present will activate the relay via the bridge and the small capacitor (10uF) should keep the rectified peaks from chattering the relay at AC (x 2) frequencies.
It's "x 2" because (say) 50Hz AC adopts a 100Hz profile when bridge rectified.
You could also use an opto-isolator fed from a bridge circuit too. This would need a smaller capacitor and a series resistor with the diode of the opto. The transistor part of the opto could switch 5V (or 3V3 or whatever DC you are using) to the arduino.
Best Answer
You don't want your Processing sketch to detect when the LED lights up. Per your description, you are touching a wire with a wand. This wire, which I will assume is some kind of switch, has to go into one of the pins on the Arduino that has been configured as an input. Your Arduino code is then responsible for detecting a change on this input, and then will set the output bit high (or low, if that's how your circuit is set up) to turn on the LED and buzzer. It is this change in the input that you will also use to make the text appear on the screen.