Week 13 -- Interfaces

I was travelling this week, so I post-hoc made the simplest possible hello-world project for this week.

The set-up here was the same as for my MVP final project (motion sensor & servo), with an HTML page sneaked into the ESP.

Surprisingly, this took only a few tries to iron out (thanks to GPT's help too). I struggled with the wifi for a while, but eventually everything worked out. Production code:

        
#include 
#include 
#include 

const char* ssid = "MLDEV";
const char* password = "[CENSORED]";

int pinIR = 44;
int servoPin = 43;

Servo myServo;
WebServer server(80);

bool isLidOpen = false;
bool webControlActive = false;
unsigned long webControlTimeout = 0;

void handleRoot() {
  server.send(200, "text/html", R"rawliteral(
    
    
    
      
      
    
    
      
ESP32 Servo Control
      Open Lid
      Close Lid
    
    
  )rawliteral");
}

void handleOpen() {
  if (!isLidOpen) {
    Serial.println("Web: Lid Open");
    myServo.write(0);
    isLidOpen = true;
    webControlActive = true;
    webControlTimeout = millis() + 5000;
    server.send(200, "text/plain", "Lid Opened");
  } else {
    server.send(200, "text/plain", "Lid is already open");
  }
}

void handleClose() {
  if (isLidOpen) {
    Serial.println("Web: Lid Close");
    myServo.write(85);
    isLidOpen = false;
    webControlActive = true;
    webControlTimeout = millis() + 5000;
    server.send(200, "text/plain", "Lid Closed");
  } else {
    server.send(200, "text/plain", "Lid is already closed");
  }
}

void setup() {
  Serial.begin(9600);

  Serial.println("Connecting to Wi-Fi...");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }
  Serial.println("\nWi-Fi connected!");
  Serial.print("Access the server at: http://");
  Serial.println(WiFi.localIP());

  pinMode(pinIR, INPUT);

  myServo.attach(servoPin, 500, 2500);
  myServo.write(85);

  server.on("/", handleRoot);
  server.on("/open", handleOpen);
  server.on("/close", handleClose);

  server.begin();
  Serial.println("Server started...");
}

void loop() {
  server.handleClient();

  if (webControlActive && millis() > webControlTimeout) {
    webControlActive = false;
  }

  if (!webControlActive) {
    int IRstate = digitalRead(pinIR);
    if (IRstate == LOW && !isLidOpen) {
      Serial.println("IR: Detected - Opening Lid");
      myServo.write(0);
      isLidOpen = true;
      delay(5000);
    } else if (IRstate == HIGH && isLidOpen) {
      Serial.println("IR: Not Detected - Closing Lid");
      myServo.write(85);
      isLidOpen = false;
    }
  }

  delay(500);
}
        
    

The main problem I faced was unreliability. I usually took 5 tries for the web interface button to successfully activate the servo. But -- hello world!

Group Assignment: Tool Comparisons

Well, I wasn't in town for this group assignment. So here's a few personal notes from looking into these tools:

• Programming Languages
  • Python
    • Pros: Easy to learn, versatile, extensive libraries. We [heart] Python
    • Cons: Slower execution speed, higher memory usage.
  • JavaScript
    • Pros: Runs in all browsers. Large ecosystem.
    • Cons: Security and injection vulnerabilities?
  • Rust
    • Pros: P E R F O R M A N C E
    • Cons: Steep learning curve
• Device Interfaces
  • I2C
    • Pros: Simple two-wire interface
    • Cons: Limited distance and speed, susceptible to noise. And hard to make work? At least struggled to make I2S (not I2C) work with microphone input and ESP32s.
  • USB
    • Pros: Universal standard, high data transfer rates.
    • Cons: Drivers?
  • MQTT
    • Pros: Lightweight, ideal for IoT applications
    • Cons: Broker?
• WebGPU
  • Pros: better performance than WebGL
  • Cons: limited browser support