Week 11 Networking and Communications

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🌐 Fab Academy: Week X - Networking and Communications

This week for networking I connected 2 ESP32-S3 boards and made them communicate wirelessly.

🔧 I soldered header pins onto the ESP32 boards so that I can attach components onto it.

🤖 Then I worked with ChatGPT to learn how to code and network between the boards.

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🧭 Step 1: Getting the MAC Address

📟 The first step was to get the MAC address for one board.
🧪 It took a couple of tries to get the code just right but then it worked!

The working code:

Mac Adress

#include <WiFi.h>

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);  // Set to Station mode
  delay(1000);
  Serial.print("MAC Address: ");
  Serial.println(WiFi.macAddress());
}

void loop() {}

📬 I had the MAC address for the receiver.

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🗣️ Step 2: Saying Hello

📡 I used this MAC address to do a simple serial print code that made them say hello to each other, to establish a connection.

Sender Code:

Transmission code

#include <WiFi.h>
#include <esp_now.h>

uint8_t peerAddress[] = {0x74, 0x4D, 0xBD, 0x97, 0x65, 0xFC};

String incomingMsg;
unsigned long lastSent = 0;

void OnDataRecv(const esp_now_recv_info_t *info, const uint8_t *data, int len) {
  incomingMsg = "";
  for (int i = 0; i < len; i++) {
    incomingMsg += (char)data[i];
  }
  Serial.print("Received: ");
  Serial.println(incomingMsg);
}

void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
  Serial.print("Send Status: ");
  Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Success" : "Fail");
}

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();

  if (esp_now_init() != ESP_OK) {
    Serial.println("ESP-NOW init failed");
    return;
  }

  esp_now_register_recv_cb(OnDataRecv);
  esp_now_register_send_cb(OnDataSent);

  esp_now_peer_info_t peerInfo = {};
  memcpy(peerInfo.peer_addr, peerAddress, 6);
  peerInfo.channel = 0;
  peerInfo.encrypt = false;
  if (!esp_now_is_peer_exist(peerAddress)) {
    esp_now_add_peer(&peerInfo);
  }
}

void loop() {
  if (millis() - lastSent > 1000) {
    const char *msg = "Hello from A";
    esp_now_send(peerAddress, (uint8_t *)msg, strlen(msg));
    lastSent = millis();
  }
}

Reciever code:

Reciever code

#include <WiFi.h>
#include <esp_now.h>

String incomingMsg;

void OnDataRecv(const esp_now_recv_info_t *info, const uint8_t *data, int len) {
  incomingMsg = "";
  for (int i = 0; i < len; i++) {
    incomingMsg += (char)data[i];
  }
  Serial.print("Received: ");
  Serial.println(incomingMsg);

  // Add sender as peer before replying
  if (!esp_now_is_peer_exist(info->src_addr)) {
    esp_now_peer_info_t peerInfo = {};
    memcpy(peerInfo.peer_addr, info->src_addr, 6);
    peerInfo.channel = 0;
    peerInfo.encrypt = false;
    esp_now_add_peer(&peerInfo);
  }

  const char *reply = "Hello from B";
  esp_now_send(info->src_addr, (uint8_t *)reply, strlen(reply));
}

void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
  Serial.print("Send Status: ");
  Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Success" : "Fail");
}

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();

  if (esp_now_init() != ESP_OK) {
    Serial.println("ESP-NOW init failed");
    return;
  }

  esp_now_register_recv_cb(OnDataRecv);
  esp_now_register_send_cb(OnDataSent);
}

void loop() {
  // Waiting for incoming messages...
}

Output from this transmission.

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💡 Step 3: Blinking the Onboard LED

🔨 Next, I built upon this code to make an onboard LED blink .
🧩 It was a task to figure out which pin the built-in LED was on, but I got it eventually!

Code for a simple LED blink:

Onboard LED blink

#ifndef LED_BUILTIN
  #define LED_BUILTIN 38  // fallback if not defined
#endif

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  delay(500);
  digitalWrite(LED_BUILTIN, LOW);
  delay(500);
}

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Development for Final project!

I am going to use ESP32s as my main board for my final project, It will be used for controlling the gas release and trigger the plasma pulse from the glove. I have strated tinkering and I will post updates when I have breakthroughs!

code:

Servo wireless control_Receiver

#include <esp_now.h>
#include <WiFi.h>
#include <ESP32Servo.h>

Servo myServo;

typedef struct struct_message {
  int xVal;
} struct_message;

struct_message receivedData;

void onReceive(const esp_now_recv_info_t *info, const uint8_t *incomingData, int len) {
  memcpy(&receivedData, incomingData, sizeof(receivedData));

  int angle = map(receivedData.xVal, 0, 4095, 0, 180);
  myServo.write(angle);

  Serial.print("Received X: ");
  Serial.print(receivedData.xVal);
  Serial.print(" | Mapped Angle: ");
  Serial.println(angle);
}

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

  myServo.attach(0); // D0 = GPIO 0
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();

  if (esp_now_init() != ESP_OK) {
    Serial.println("ESP-NOW Init Failed");
    return;
  }

  esp_now_register_recv_cb(&onReceive);
}

void loop() {
  // nothing here; waiting for joystick input
}

Servo Wireless Control_Transmission

#include <esp_now.h>
#include <WiFi.h>

#define JOYSTICK_X_PIN 0  // D0 -> GPIO 0

uint8_t receiverMac[] = {0x74, 0x4D, 0xBD, 0x97, 0x65, 0xFC};  // Updated MAC

typedef struct {
  int xVal;
} JoystickData;

JoystickData dataToSend;

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

  // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_STA);
  Serial.println("Transmitter MAC: " + WiFi.macAddress());

  // Init ESP-NOW
  if (esp_now_init() != ESP_OK) {
    Serial.println("ESP-NOW Init Failed");
    return;
  }

  // Register peer
  esp_now_peer_info_t peerInfo = {};
  memcpy(peerInfo.peer_addr, receiverMac, 6);
  peerInfo.channel = 0;
  peerInfo.encrypt = false;

  if (!esp_now_add_peer(&peerInfo)) {
    Serial.println("Failed to add peer");
  } else {
    Serial.println("Peer added");
  }

  // Read Joystick X only
  pinMode(JOYSTICK_X_PIN, INPUT);
}

void loop() {
  dataToSend.xVal = analogRead(JOYSTICK_X_PIN);
  esp_now_send(receiverMac, (uint8_t*)&dataToSend, sizeof(dataToSend));
  Serial.print("Sent X: ");
  Serial.println(dataToSend.xVal);
  delay(100);  // Adjust as needed
}