[esp] Add ESP examples.

README.md

@@ -2,15 +2,16 @@
 
 This repository is a collection of useful code snippets and configurations.
 
-```
+```bash
 github.com/shaunrd0/klips/
 ├── ansible     # Ansible roles, playbooks, and examples
 ├── blockchain  # Blockchain related project templates and examples
 ├── cpp         # C++ programs, datastructures, and other examples
 ├── dotnet      # .NET projects and examples
+├── esp         # ESP32 projects and examples
 ├── figlet      # Figlet fonts I like :)
 ├── javascript  # Javascript projects and examples
-├── python      # Python scripts or tools I've made   
+├── python      # Python scripts and tools I've made
 ├── README.md
 └── scripts     # Bash scripts
 ```

ansible/README.md

@@ -1,4 +1,4 @@
-# Ansible 
+# ansible
 
 A few simple roles / plays I've put together in learning how to use Ansible can be found under their corresponding directories.
 

blockchain/eth/truffle-solidity/README.md

@@ -1,3 +1,4 @@
+# blockchain
 
 A template project for getting started working on the Ethereum blockchain.
 This project comes with basic packages for compiling and deploying Solidity contracts with Truffle.

cpp/README.md

@@ -1,4 +1,4 @@
-# Cpp
+# cpp
 
 ```bash
 shaunrd0/klips/cpp/

dotnet/README.md

@@ -1,4 +1,4 @@
-# Dotnet
+# dotnet
 
 ```bash
 shaunrd0/klips/dotnet/

esp/cpp/01_led-button/01_led-button.ino

@@ -0,0 +1,38 @@
+// set pin numbers
+const int buttonPin = 4;  // the number of the pushbutton pin
+const int ledPin =  5;    // the number of the LED pin
+
+// variable for storing the pushbutton status
+int buttonState = 0;
+
+bool light_on = false;
+bool handled = false;
+
+void setup() {
+  Serial.begin(115200);
+  // initialize the pushbutton pin as an input
+  pinMode(buttonPin, INPUT);
+  // initialize the LED pin as an output
+  pinMode(ledPin, OUTPUT);
+}
+
+void loop() {
+  // read the state of the pushbutton value
+  buttonState = digitalRead(buttonPin);
+  // check if the pushbutton is pressed.
+  if (buttonState == HIGH) {
+    if (!handled) {
+      Serial.println("Handling button pressed.");
+      light_on = !light_on;
+      handled = true;
+      digitalWrite(ledPin, light_on ? HIGH : LOW);
+    }
+    // turn LED on
+  } else {
+    if (handled) {
+      Serial.println("Reset button handled state.");
+      handled = false;
+
+    }
+  }
+}

esp/cpp/01_led-button/README.md

@@ -0,0 +1,5 @@
+# 01_led-button
+
+![schematic](./schematic.png)
+
+Simple LED controlled by an on-board button.

esp/cpp/02_led-button-web/02_led-button-web.ino

@@ -0,0 +1,183 @@
+#include <WiFi.h>
+
+//
+// Web server project globals
+
+// Replace with your network credentials
+const char* ssid = "network-name";
+const char* password = "password";
+
+WiFiServer server(80);
+
+// Variable to store the HTTP request
+String header;
+
+// Current time
+unsigned long currentTime = millis();
+// Previous time
+unsigned long previousTime = 0;
+// Define timeout time in milliseconds (example: 2000ms = 2s)
+const long timeoutTime = 2000;
+
+//
+// Button / light project globals
+
+// set pin numbers
+const int buttonPin = 4;  // the number of the pushbutton pin
+const int ledPin =  5;    // the number of the LED pin
+
+// variable for storing the pushbutton status
+int buttonState = 0;
+
+bool light_on = false;
+bool handled = false;
+
+void setup() {
+  Serial.begin(115200);
+  // initialize the pushbutton pin as an input
+  pinMode(buttonPin, INPUT);
+  // initialize the LED pin as an output
+  pinMode(ledPin, OUTPUT);
+
+  // wait for the Serial Monitor to be open
+  while (!Serial) {
+    delay(100);
+  }
+
+  // Connect to Wi-Fi network with SSID and password
+  Serial.print("Connecting to ");
+  Serial.println(ssid);
+  WiFi.begin(ssid, password);
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+  // Print local IP address and start web server
+  Serial.println("");
+  Serial.println("WiFi connected.");
+  Serial.println("Web Server IP address: ");
+  Serial.println(WiFi.localIP());
+  server.begin();
+}
+
+// Handles the on-board button press.
+void handleButtonPress() {
+  // read the state of the pushbutton value
+  buttonState = digitalRead(buttonPin);
+  // check if the pushbutton is pressed.
+  if (buttonState == HIGH) {
+    if (!handled) {
+      Serial.println("Handling button pressed.");
+      light_on = !light_on;
+      handled = true;
+      digitalWrite(ledPin, light_on ? HIGH : LOW);
+    }
+    // turn LED on
+  } else {
+    if (handled) {
+      Serial.println("Reset button handled state.");
+      handled = false;
+    }
+  }
+}
+
+void displayPinState(WiFiClient client, int gpio_pin, bool state) {
+  // Display current state, and ON/OFF buttons for GPIO <gpio_pin>
+  client.println(String("<p>GPIO ") + String(gpio_pin) + String(" - Current State ") + String(state ? "ON" : "OFF") + String("</p>"));
+  // If the output state is off, it displays the ON button
+  if (state) {
+    client.println(String("<p><a href=\"/") + String(gpio_pin) + String("/off\"><button class=\"button button2\">OFF</button></a></p>"));
+  } else {
+    client.println(String("<p><a href=\"/") + String(gpio_pin) + String("/on\"><button class=\"button\">ON</button></a></p>"));
+  }
+}
+
+void handleStateChange(WiFiClient client, int gpio_pin) {
+  if (header.indexOf(String("GET /") + String(gpio_pin) + String("/on")) >= 0) {
+    Serial.println(String("GPIO ") + String(gpio_pin) + String(" on"));
+    light_on = true;
+    digitalWrite(gpio_pin, HIGH);
+  } else if (header.indexOf(String("GET /") + String(gpio_pin) + String("/off")) >= 0) {
+    Serial.println(String("GPIO ") + String(gpio_pin) + String(" off"));
+    light_on = false;
+    digitalWrite(gpio_pin, LOW);
+  }
+}
+
+void loop() {
+  WiFiClient client = server.available();   // Listen for incoming clients
+
+  handleButtonPress();
+
+  if (client) {                             // If a new client connects,
+    currentTime = millis();
+    previousTime = currentTime;
+    Serial.println("New Client.");          // print a message out in the serial port
+    Serial.println("Web Server IP address: ");
+    Serial.println(WiFi.localIP());
+
+    String currentLine = "";                // make a String to hold incoming data from the client
+    while (client.connected() && currentTime - previousTime <= timeoutTime) {  // loop while the client's connected
+      // Also handle the button press in this loop to not miss events.
+      handleButtonPress();
+
+      currentTime = millis();
+      if (client.available()) {             // if there's bytes to read from the client,
+        char c = client.read();             // read a byte, then
+        Serial.write(c);                    // print it out the serial monitor
+        header += c;
+        if (c == '\n') {                    // if the byte is a newline character
+          // if the current line is blank, you got two newline characters in a row.
+          // that's the end of the client HTTP request, so send a response:
+          if (currentLine.length() == 0) {
+            // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
+            // and a content-type so the client knows what's coming, then a blank line:
+            client.println("HTTP/1.1 200 OK");
+            client.println("Content-type:text/html");
+            client.println("Connection: close");
+            client.println();
+
+            // turns the GPIOs on and off
+            // Display the HTML web page
+            client.println("<!DOCTYPE html><html>");
+            client.println("<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">");
+            client.println("<link rel=\"icon\" href=\"data:,\">");
+            // CSS to style the on/off buttons
+            // Feel free to change the background-color and font-size attributes to fit your preferences
+            client.println("<style>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}");
+            client.println(".button { background-color: #4CAF50; border: none; color: white; padding: 16px 40px;");
+            client.println("text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}");
+            client.println(".button2 {background-color: #555555;}</style></head>");
+
+            //
+            // Web Page Heading
+            client.println("<body><h1>ESP32 Web Server</h1>");
+            //
+            // Web Page Body Contents
+
+            // Button Controls
+            displayPinState(client, ledPin, light_on);
+
+            //
+            // Close Web Page Body / Heading
+            client.println("</body></html>");
+            // The HTTP response ends with another blank line
+            client.println();
+            // Break out of the while loop
+            break;
+          } else { // if you got a newline, then clear currentLine
+            currentLine = "";
+          }
+        } else if (c != '\r') {  // if you got anything else but a carriage return character,
+          currentLine += c;      // add it to the end of the currentLine
+        }
+      }
+    }
+    // Clear the header variable
+    header = "";
+    // Close the connection
+    client.stop();
+    Serial.println("Client disconnected.");
+    Serial.println("");
+  }
+}

esp/cpp/02_led-button-web/README.md

@@ -0,0 +1,11 @@
+# 02_led-button-web
+
+![schematic](./schematic.png)
+
+This example uses the same schematic as [01_led-button](../01_led-button/).
+
+The only difference is that you can also control the button through a web browser from any device connected to your local network.
+
+This example was adapted from the example code in the [Arduino ESP32 API reference](https://docs.espressif.com/projects/arduino-esp32/en/latest/api/wifi.html#wi-fi-ap-example).
+
+![screenshot](./screenshot.png)

esp/cpp/README.md

@@ -0,0 +1,21 @@
+# esp
+
+```bash
+shaunrd0/klips/esp/
+├── 01_led-button               # Simple LED circuit controlled by an on board button.
+├── 02_led-button-web           # LED controlled by a button or within a web browser.
+├── ESP32-basic-starter-kit.pdf # PDF for tutorials in ESP32 starter kit.
+├── ESP32-dev-module.png
+└── README.md
+```
+
+This directory contains ESP32 projects largely adapted from the examples in [ESP32-basic-starter-kit.pdf](./ESP32-basic-starter-kit.pdf).
+
+The APIs in the original examples paired with this PDF have changed, and I decided to do some different things with the code and/or circuits, but the original code can be [found here](https://www.dropbox.com/scl/fo/6znlij3eb23ih4jxcpv2w/AKvB1t9CCUgoVRVtGen8Yrw?rlkey=z84anl0hs940qf9fpl7l8q8q2&e=1&dl=0).
+
+The board selected in [Arduino IDE](https://www.arduino.cc/en/software) is ESP32 Dev Module -
+
+![ESP32 Dev Module](./ESP32-dev-module.png)
+
+[Arduino ESP32 GitHub](https://github.com/espressif/arduino-esp32) \
+[Arduino ESP32 API reference](https://docs.espressif.com/projects/arduino-esp32/en/latest/libraries.html)

javascript/README.md

@@ -1,9 +1,9 @@
-# Javascript
+# javascript
 
 This directory contains Javascript projects and examples that I've made.
 
-```
-github.com/shaunrd0/klips/javascript
+```bash
+shaunrd0/klips/javascript
 ├── webgl      # Examples of using WebGL within JS
 └── README.md
 ```

python/README.md

@@ -1,3 +1,4 @@
+# python
 
 This directory contains a collection of Python scripts or CLI tools that I've made.
 Each of these projects provide a `requirements.txt` that can be used to