10. Output devices

Group assignment:

Measure the power consumption of an output device. Document your work on the group work page and reflect on your individual page what you learned.

Individual assignment:

Add an output device to a microcontroller board you’ve designed and program it to do something. Learning outcomes

Individual Assignment

For the output devices week i have decided Oled as my output Design .

I tried to use the autorouter to the PCB design . There was some issues . It didnot work so i did the routing manually .

nothing worked

This is the Final Circuit Diagram that i routed manualy .

Then i have Uploaded to Gerber2Png and used Doubleside to Gernerate the Png files Required for milling .

added capacitors to rotary encoders as my instructor instructed .

The below image is my Final circuit diagram . .

I have milled the PCb then i Realized that the Led is not connected Properly and then i found the connections are wrong and then i used a heat Gun to De solder it . It was a mistake . As the Heat Gun burned my led . I Told my instructor about this and he told there is a different way on how to use with LEDS .

The below image is the heated led where the top portion of the led has burned Off .

How to check the Pcb before connecting to your Laptop?

For that you could use the help of a power supply where the input voltage and current are set . for me the Input volatge was 5v and the ampere was set to 0.1 Ampere in channel 1.

Steps > choose the chanel > > Set the current and the voltage >connect the Probe accordingly the Red to the vcc and then black probe to the Ground > click the output .

If the current delivered is constant and if there is no over current drawn you could say the circuit is not short . If the circuit is short it will try to withdraw over current and you may see something like cc. (since the current is limited in the power supply as we have set it already it wont be a problem ). which means the circuit is short and you should check the connections . if it is short then connected to laptop . it may damage your laptop driver .

i tested the normal encoder codes from the last week . it was not working .

OLED DISPLAY .

OLED, or Organic Light-Emitting Diode, display is a type of electronic visual display technology that uses organic compounds to emit light when an electric current is applied. Unlike traditional LCD (Liquid Crystal Display) screens, which require a backlight to illuminate pixels, OLED displays are self-emissive. This means that each individual pixel in an OLED display emits its own light, allowing for deep blacks, high contrast ratios, and vibrant colors. OLED technology is known for its advantages, including faster response times, wider viewing angles, and reduced power consumption compared to some other display technologies.

Step	Description
1. Install Libraries	Install the Adafruit_GFX and Adafruit_SSD1306 libraries via the Arduino Library Manager. These libraries simplify drawing graphics and interfacing with SSD1306-based OLEDs.
2. Hardware Connections	Connect the OLED’s SDA and SCL pins to GPIO 21 and 22 of the ESP32, respectively. Ensure proper power connections (3.3V and GND).
3. Initialize Display	Use display.begin(SSD1306_I2C_ADDRESS, SDA, SCL) in your setup code to initialize the display with its I2C address (commonly 0x3C).
4. Clear and Setup Screen	Use display.clearDisplay() to clear the screen before drawing and display.display() to update the content on the OLED.
5. Draw Graphics/Text	Utilize functions like display.setTextSize(), display.setTextColor(), and display.setCursor() to add text or shapes. For example, draw a rectangle using display.drawRect(x, y, width, height, color).
6. Display Dynamic Data	Update content dynamically by clearing the screen and rewriting data in a loop. For instance, use a timer to fetch real-time data like time from an NTP server.
7. Optimize Power Consumption	Turn off the display when idle using display.ssd1306_command(SSD1306_DISPLAYOFF) to save power in battery-powered applications.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SDA_PIN 21
#define SCL_PIN 22

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void setup() {
Serial.begin(115200);

// Initialize I2C with specific pins
Wire.begin(SDA_PIN, SCL_PIN);

if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
Serial.println(F("SSD1306 allocation failed"));
for(;;);
}

// Clear the buffer
display.clearDisplay();

// Set text properties
display.setTextSize(2);
display.setTextColor(WHITE);
display.setCursor(25, 25);

// Display "Hello"
display.println("Hello");

// Show on the display
display.display();
}

void loop() {
// Your main code can go here
}

![oledtime.jpg](../images/WEEK10/oledtime.jpg)

Displaying Time Using NTP Servers

Step	Description
Include Libraries	Add WiFi, NTPClient, and Adafruit_SSD1306 libraries to your project
Initialize WiFi	Connect to a WiFi network using your SSID and password
Configure NTP Client	Set up NTPClient with a pool server (e.g., “pool.ntp.org”)
Fetch Time	Use NTPClient’s update() and getFormattedTime() functions
Display on OLED	Write the fetched time to the OLED display using Adafruit_SSD1306 functions
Periodic Updates	Implement a timer to update the displayed time every minute

#include <WiFi.h>
#include <time.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// Network credentials
const char* ssid = "iPhone";
const char* password = "abin1234";

// NTP server settings
const char* ntpServer = "pool.ntp.org";
const long gmtOffset_sec = 19800;  // GMT +5:30 for India in seconds
const int daylightOffset_sec = 0;  // No daylight saving in India

// OLED display settings
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SDA_PIN 21
#define SCL_PIN 22

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Connection timeout
#define CONNECTION_TIMEOUT 10

// Declare timeinfo globally
struct tm timeinfo;

void setup() {
  Serial.begin(115200);

  // Initialize I2C with specific pins
  Wire.begin(SDA_PIN, SCL_PIN);

  // Initialize OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.clearDisplay();
  display.setTextColor(WHITE);

  // Connect to Wi-Fi with timeout
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("Connecting to WiFi...");
  display.display();

  int timeout_counter = 0;
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    timeout_counter++;
    if(timeout_counter >= CONNECTION_TIMEOUT*2) {
      Serial.println("Connection failed, restarting...");
      display.clearDisplay();
      display.setCursor(0, 0);
      display.println("WiFi connection failed");
      display.println("Restarting...");
      display.display();
      delay(2000);
      ESP.restart();
    }
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("Connected!");
  display.println("Getting time...");
  display.display();

  // Initialize and get time
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);

  // Wait for time to be set
  int retry = 0;
  while(!getLocalTime(&timeinfo) && retry < 10) {
    Serial.println("Failed to obtain time");
    delay(1000);
    retry++;
  }

  if(retry >= 10) {
    display.clearDisplay();
    display.setCursor(0, 0);
    display.println("Failed to get time");
    display.println("Restarting...");
    display.display();
    delay(2000);
    ESP.restart();
  }
}

void loop() {
  if(!getLocalTime(&timeinfo)) {
    Serial.println("Failed to obtain time");
    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(0, 0);
    display.println("Failed to get time");
    display.display();
    return;
  }

  // Format time as HH:MM:SS
  char timeString[9];
  strftime(timeString, sizeof(timeString), "%H:%M:%S", &timeinfo);

  // Format date as DD-MM-YYYY
  char dateString[11];
  strftime(dateString, sizeof(dateString), "%d-%m-%Y", &timeinfo);

  // Format day of week
  char dowString[10];
  strftime(dowString, sizeof(dowString), "%A", &timeinfo);

  // Display time on OLED
  display.clearDisplay();

  // Show time in large font
  display.setTextSize(2);
  display.setCursor(10, 5);
  display.println(timeString);

  // Show date in smaller font
  display.setTextSize(1);
  display.setCursor(20, 30);
  display.println(dateString);

  // Show day of week
  display.setCursor(20, 45);
  display.println(dowString);

  display.display();

  // Also print to serial monitor
  Serial.println(&timeinfo, "%A, %B %d %Y %H:%M:%S");

  delay(1000);
}

CONCLUSION

Throughout this project, I gained valuable hands-on experience in PCB design, component handling, and troubleshooting. I learned important lessons about proper desoldering techniques, especially for sensitive components like LEDs. The implementation of the OLED display and rotary encoders has enhanced my understanding of integrating different electronic components and programming them effectively.

FILES

GERBER

SCHEMATICS

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Last update: April 1, 2025