The digital input and output of Arduino

So, let’s talk about Arduino and its digital inputs! The Arduino has these labeled pins for both analog and digital inputs, and they’re super important for handling binary signals in electronics.
Digital inputs are your go-to for tasks like pressing buttons or getting signals from cool stuff like PIR sensors – it makes your projects interact with the real world.
Now, when you’re dealing with the limitations on digital input or output pins, you can use flexible ones like pin 9.
But a little tip: steer clear of pins 0 and 1 to keep your connection with the PC smooth and your code cleaner since those two are tied up with firmware communication.
For instance, I like to connect a switch to pin 9 and declare a macro constant for easy reference.
This little trick definitely boosts your code readability and maintainability.
Remember, make sure to set the pin mode according to how you’ve wired it up!.

If you’re diving into the Arduino world, you’ll want to check out the circuit diagram for the Arduino Uno Revision 3 to make sure your switches work properly with pull-up or pull-down resistors.
Just a heads up: when using the internal pull-up configuration, it’s best to steer clear of pins 0 and 1 since they link to serial communication, which could mess with your program if not handled right.
A fun example to start with is using pin 8 for an LED in a simple project that shows how to control those digital outputs.
Once you set the pin direction as output, you can make that LED blink every second, serving as a straightforward way to test if your pins are working as they should!.

When you’re working with your Arduino, you might find yourself in a bit of a loop—literally! Since the switch’s status remains unknown when the device starts up, it’s a good idea to run an infinite loop that turns your device on for 1 second and off for another second, over and over.
For better data management, I recommend using data types like uint8_t and uint16_t , but watch out for those pesky misalignments often called indentation .
If that happens, just press Ctrl T (or Command T on a Mac) to neatly format the lines for you.
After you save your work, your 8-bit data type will compile and check for any issues.
Then, just hit that upload button—Arduino prefers to call it ‘upload’ instead of ‘download’—and you’re good to go! Finally, you can check the state using digital read pins..

So, letting your digital output do its thing is pretty straightforward! You just need to set your pin mode to output, then you can blast a digitalWrite out there, throw in a delay , and hit another digitalWrite .
Just remember that every time through the loop, it resets some of those values, including your button state, which means you might lose track of what the button was doing before.
Now, when you check in with that if statement, if your button state is high but flips to low when pressed, guess what? That means the button is live! In that case, you make your digital light pin for the LED shine bright; otherwise, it stays in its previous low state..

So, here’s the deal: when you’ve pressed a button and the LED is lit up, the next press will turn it off.
The code takes care of tracking whether the button is pressed or not by updating a variable called pState, using macro constants for both the LED and the switch, and ensuring the pin mode is set right.
As the loop runs, it checks the button’s state, figuring out if it’s pressed or not to control that LED.
After that, it updates the previous state, waits a quick 10ms, and then goes again while keeping the code nice and tidy for uploading.
For this session, we played around with Arduino’s GPIO pins for digital control, but we’re definitely looking to dive into analog control in the future!.