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XIAO ESP32C5 ESP-Mesh Audio

ESP-WIFI-MESH​

The following is the official introduction to ESP-WIFI-MESH by Espressif Systems:

ESP-WIFI-MESH is a wireless communication network with nodes organized in a mesh topology using the simultaneous AP-STA feature on Espressif SoCs. It provides a self-forming and self-healing network, with ease of deployment. The network topology of ESP-WIFI-MESH can scale up to 1000 nodes in large areas, without requiring any specific Wi-Fi infrastructure support. ESP-WIFI-MESH can also be used to cover Wi-Fi blind spots in home-deployment scenarios where the Wi-Fi signal cannot be reached.

It features the following characteristics:

  1. Easy and Secure Setup : Mobile app + Bluetooth LE network configuration is supported, enabling quick addition of new nodes and secure delivery of configurations.
  2. Self-forming and Self-healing : Nodes will automatically connect/reconnect, and the network can form automatically and self-heal when a node fails.
  3. No Extra Gateways Required : No additional gateways or infrastructure are required. The Mesh network can scale up to thousands of nodes, making it suitable for large-scale deployments.
  4. IP Connectivity : All nodes support IP communication, enabling both interconnection among themselves and access to external networks (via root-node NAT or bridging).
  5. Secure by Design : Based on standard Wi-Fi, communications between nodes can adopt WPA2 encryption to ensure secure data transmission.
  6. Applications : It is applicable to various scenarios such as smart lighting, smart homes, automation control, and networking in large-scale venues (e.g., parking lots, factories, shared spaces).

For more detailed information, please refer to the official link of Espressif Systems :

ESP-Mesh_Audio​

Next, we will use a XIAO ESP32-C5, a router supporting the 5 GHz frequency band, and a computer to simulate 5 GHz band audio transmission in a Mesh node scenario.
Here, your computer acts as a Mesh child node, sending data via a 5 GHz router; the C5 acts as a Mesh root node, receiving data.

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If you do not have a router supporting the 5 GHz frequency band at home, you can enable your mobile phone's hotspot, set it to the 5 GHz frequency band, and ensure that your computer is connected to this hotspot.

Create an Arduino Project​

Copy the following code, and modify the ssid and password to the name and password of the 5 GHz frequency band router you are using.

#include <WiFi.h>
#include <WiFiUdp.h>

const char* ssid = "Your_5G_Router_SSID";
const char* password = "Your_Router_Password";
#define UDP_PORT 4444

WiFiUDP udp;
uint8_t packetBuffer[1024]; // Buffer for storing received UDP packets

void setup() {
  Serial.begin(115200);
  
  // Connect to WiFi
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  
  Serial.print("Connecting to 5GHz WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nConnected!");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());

  // Start UDP listening
  udp.begin(UDP_PORT);
  Serial.printf("Listening on UDP port %d\n", UDP_PORT);
}

void loop() {
  int packetSize = udp.parsePacket();
  if (packetSize) {
    // Read received data
    int len = udp.read(packetBuffer, 1024);
    
    // Statistics and print: size of received packet, and signal strength (RSSI)
    // Signal strength is crucial for 5GHz audio transmission
    Serial.printf("[RECV] %d bytes from %s, RSSI: %d dBm\n", 
                  len, udp.remoteIP().toString().c_str(), WiFi.RSSI());
                  
    // If you have an I2S speaker, you can call i2s_write here for playback
  }
}

Get the IP Address​

Upload the code to the XIAO ESP32-C5, open the Serial Monitor, and the connected IP address will be printed if it successfully connects to the 5 GHz WiFi router.

Create a Python Script​

Before using the Python script, you need to install the Python 3 environment first. You can search for the corresponding installation tutorials online for details.

Create a file named send_audio.py in any folder on Windows, and copy the following Python code into it.。

Fill in the IP address printed by the Serial Monitor of the Arduino IDE into the TARGET_IP variable in the code.

import socket
import time
import random

# Set the target IP (View the IP printed out by the serial port of C5)
TARGET_IP = "192.168.x.x" # <--- Modify here!!!
TARGET_PORT = 4444

# Simulated Audio Parameters
# 16kHz sampling, 16-bit, mono -> 32000 bytes per second
# Send one packet every 20ms -> Each packet is 640 bytes
PACKET_SIZE = 640 
INTERVAL = 0.02 # 20ms

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
print(f"Start sending simulated audio to {TARGET_IP}:{TARGET_PORT}...")

sequence = 0

try:
    while True:
        # Generate simulated data (add serial numbers to facilitate packet loss detection)
        # The first 4 bytes are the serial numbers, followed by random noise
        payload = sequence.to_bytes(4, byteorder='big') + random.randbytes(PACKET_SIZE - 4)
        
        sock.sendto(payload, (TARGET_IP, TARGET_PORT))
        print(f"Sent packet #{sequence}, size: {len(payload)}")
        
        sequence += 1
        time.sleep(INTERVAL) # Control the transmission frequency

except KeyboardInterrupt:
    print("Stopped.")
    sock.close()

Run the Script File​

Right-click in the folder where send_audio.py is stored and open the terminal in this folder.
Enter python send_audio.py to execute the script. After a successful connection, it will send audio data to the XIAO ESP32-C5 every 20 ms.

The monitor window of the Arduino IDE will return the IP address and byte data of your computer, as well as the signal strength of the connected 5 GHz WiFi.

Congratulations! At this point, you have learned how to transmit audio over the 5 GHz WiFi band, and more innovations are waiting for you to realize!

Tech Support & Product Discussion​

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