Individual Assignment: Add an output device to a microcontroller board you've designed and program it to do something.

This week, Neil introduced us to output devices and shared several examples we could explore. The task was to connect an output device to a board we designed, program it, and make it work. For this assignment, I decided to create a board with multiple LEDs simulating a traffic light, where each LED turns on individually based on a programmed time sequence. I used the development board I manufactured during the Electronics Production week, which features an ATtiny412 chip with analog and digital inputs and outputs.

1. Planning the Output Device

The ATtiny412 board I designed has several pins available for digital outputs. For this project, I chose to use three digital pins to control three LEDs (red, yellow, and green) to mimic a traffic light sequence. Below is an image showing the pinout of the board.

2. Programming Setup

To upload the program to the ATtiny412, I used an Arduino Nano as a programmer, communicating through the UPDI port. This setup allowed me to easily transfer the code to the microcontroller.

3. Selecting Components

I selected the electronic components needed for the project: three LEDs (red, yellow, green) and a 330Ω resistor for each LED to limit current. These components were chosen to ensure safe operation with the 5V supply of the board.

4. PCB Fabrication

I updated the PCB design from Week 8 to include headers for the LEDs and resistors. After exporting the Gerber files, I configured the toolpaths in FlatCAM and used the SRM-20 milling machine to fabricate the board.

5. Soldering Components

I soldered the ATtiny412, resistors, LEDs, and connectors onto the PCB. Each LED was connected to a digital pin (e.g., pins 2, 3, and 4) through its respective resistor, ensuring proper current flow and functionality.

6. Programming the Traffic Light Sequence

I wrote a program in the Arduino IDE to control the LEDs in a traffic light sequence: green on for 5 seconds, yellow on for 2 seconds, and red on for 5 seconds. Below is the code I used:

#define RED_PIN 2
#define YELLOW_PIN 3
#define GREEN_PIN 4

void setup() {
    pinMode(RED_PIN, OUTPUT);
    pinMode(YELLOW_PIN, OUTPUT);
    pinMode(GREEN_PIN, OUTPUT);
}

void loop() {
    digitalWrite(GREEN_PIN, HIGH);   // Green ON
    digitalWrite(YELLOW_PIN, LOW);
    digitalWrite(RED_PIN, LOW);
    delay(5000);                     // Wait 5 seconds

    digitalWrite(GREEN_PIN, LOW);
    digitalWrite(YELLOW_PIN, HIGH);  // Yellow ON
    digitalWrite(RED_PIN, LOW);
    delay(2000);                     // Wait 2 seconds

    digitalWrite(GREEN_PIN, LOW);
    digitalWrite(YELLOW_PIN, LOW);
    digitalWrite(RED_PIN, HIGH);     // Red ON
    delay(5000);                     // Wait 5 seconds
}
                                        

The code was uploaded to the ATtiny412 using the Arduino Nano programmer.

7. Testing the Operation

After uploading the program, I powered the board and tested the sequence. The LEDs turned on and off as expected, simulating a traffic light cycle. Below is a video demonstrating the operation: