Introduction
Building your own microcontroller circuit at home can be an incredibly rewarding and educational experience. In this article, I will walk you through the steps I took to create a simple DIY microcontroller circuit using common components that most hobbyists have lying around.
The circuit I built allows me to read analog sensor data, control LEDs, and drive small motors - all things that are useful for homemade robots and other electronic projects. Best of all, the design and component selection is unique enough that nobody else will know exactly how my circuit works!
Gather the Required Components
The great thing about this project is that it uses common components that are easy to source. Here is what you will need to follow along:
Microcontroller Board
For the brains of the operation, I used an Arduino Nano microcontroller board. The Nano packs the Atmel ATmega328 8-bit AVR microcontroller in a small footprint and can be picked up for less than $5.
Other Arduino boards like the Uno or Pro Mini would also work. Just make sure you have one that can operate at 5V.
Breadboard
To easily connect components to the Nano, I used a 400 tie point breadboard. Breadboards allow you to prototype circuits quickly without soldering.
Resistors
I needed only two resistors - a 10K ohm resistor to act as a pull-up on an input pin and a 470 ohm resistor to limit current to an LED.
Capacitor
A 0.1uF ceramic capacitor helps filter power to the microcontroller.
LEDs
For outputs, I used a red LED and a green LED.
Potentiometer
To provide an analog input, I used a 10K ohm potentiometer. This acts as an adjustable voltage divider.
Miscellaneous
I also used jumper wires to make connections and a 9V battery with barrel jack to power the circuit.
That's it for components! Just a handful of basic parts capable of creating a surprising amount of functionality.
Prototype the Circuit
With all the components ready, it is time to build the circuit. This is the general process I followed:
Set up the microcontroller
First, insert the Nano into the breadboard. Place it across the center trench with the USB port hanging off the side.
Connect jumper wires from the 5V pin to the power rails (red lines) on each side and jumper the GND pin to the ground rails (blue lines) on each side.
Add the capacitor
Insert the 0.1 uF capacitor across the 5V and GND pins on the Nano. This helps filter noise from the input power.
Connect the potentiometer
Place the 10K potentiometer in the breadboard. Use jumpers to connect the outside pins to power and ground.
Connect the middle pin to analog input A0 on the Nano. This creates a voltage divider circuit allowing the microcontroller to read the variable voltage.
Add the LEDs
Put the red and green LEDs in the breadboard with their longer legs on the positive rail.
Use a 470 ohm resistor in series with each LED and jumper from the other leg to Nano pins D5 and D6.
Complete the pull-up
Run a jumper from the D4 pin on the Nano to one leg of the 10K resistor. Connect the other leg to positive voltage.
This pull-up resistor ensures the input reads high when the button is not pressed.
Connect power
Finally, connect the 9V battery to the barrel jack on the Nano to complete the circuit.
Program the Microcontroller
Now for the software! I used the Arduino IDE to program my Nano with the following pseudocode:
```cpp
// Set pin modes
Set D5 and D6 as outputs
Set A0 as analog input
Set D4 as input with pullup
Void Loop()
{
// Read analog value
sensorValue = analogRead(A0);
// Control LED brightness based on value
analogWrite(D5, sensorValue / 4);
// Turn on LED when button pressed
If (D4 is LOW) {
digitalWrite(D6, HIGH);
}
Else {
digitalWrite(D6, LOW);
}
// Small delay
delay(10);
}
```
This allows me to control the green LED brightness based on the analog input while turning the red LED on when a button connected to D4 is pressed.
The key is customizing the program to match your unique circuit structure - that's what makes it different than any other Arduino example out there!
Conclusion
Building this simple DIY microcontroller circuit provided an excellent learning experience that I was able to customize exactly to my needs. I now have a unique project under my belt that introduces me to working with microcontrollers, breadboards, sensors, and outputs.
The whole project was relatively inexpensive by sourcing common components and took just an afternoon to put together. I encourage you to try a similar build yourself and see what unique circuits you can come up with! Let me know if you have any other questions.