Week 11: Networking and Communication

Overview

This week, I built on Output Week by designing a microcontroller system where a button on one ESP32 board communicates with another ESP32 board to control a linear actuator. The goal is to integrate this system into my final project for a voice-activated or facial-recognition-enabled door lock.

The primary challenge was establishing a stable Wi-Fi connection between the two ESP32 devices. Some issues encountered included weak Wi-Fi signals, incorrect IP configurations, and inconsistent connections. To address these:

• Placed the ESP32 devices within strong Wi-Fi coverage.
• Used static IPs for reliable communication.
• Implemented a Wi-Fi reconnection routine for better stability.

Process

Below are the steps I followed:

1. Designed and tested a new PCB board for the ESP32 microcontroller to ensure proper connections for the button and linear actuator (see schematics below).
2. Implemented server-client communication using the ESP32's Wi-Fi capabilities.
3. Tested the system by pressing the button on the client board, which triggered the actuator on the server board.

Server Code (ESP32 with Linear Actuator)

#include <WiFi.h>
#include <WebServer.h>

const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

WebServer server(80);
const int actuatorPin = 9;

void handleExtend() {
  digitalWrite(actuatorPin, HIGH);
  server.send(200, "text/plain", "Actuator extended");
  delay(1000);
  digitalWrite(actuatorPin, LOW);
}

void setup() {
  Serial.begin(115200);
  pinMode(actuatorPin, OUTPUT);
  digitalWrite(actuatorPin, LOW);

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }

  server.on("/extend", handleExtend);
  server.begin();
}

void loop() {
  server.handleClient();
}
    

Client Code (ESP32 with Button and LED)

#include <WiFi.h>
#include <HTTPClient.h>

const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";
const char* serverIP = "SERVER_IP_ADDRESS";
const int buttonPin = 20;
const int ledPin = 9;

void setup() {
  Serial.begin(115200);
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
}

void loop() {
  if (digitalRead(buttonPin) == LOW) {
    digitalWrite(ledPin, HIGH);
    delay(100);
    if (WiFi.status() == WL_CONNECTED) {
      HTTPClient http;
      String url = String("http://") + serverIP + "/extend";
      http.begin(url);
      int httpResponseCode = http.GET();
      http.end();
    }
    delay(1000);
    digitalWrite(ledPin, LOW);
  }
}
    

Videos & Final Results