UDP packet strange characters

Using Arduino Programming Questions
#1

I successfully transmit UDP packet from d1 mini to another d1 mini, however in serial monitor, I am seeing other random characters and numbers (:urn 1) I did not call for. What is this and how to avoid?

78

Code for Server Side

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>

#define WIFI_SSID "XXXX"
#define WIFI_PASS "XXXX"

// Set AP credentials
#define AP_SSID "XXXX"
#define AP_PASS "XXXX"
#define AP_CHANNEL 1
#define AP_HIDDEN true
#define AP_MAX_CON 8
 
// UDP
WiFiUDP UDP;
IPAddress local_IP(192,168,4,1);
IPAddress gateway(192,168,4,1);
IPAddress subnet(255,255,255,0);
#define UDP_PORT 4010
 
// UDP Buffer
char packetBuffer[UDP_TX_PACKET_MAX_SIZE];

ESP8266WebServer server(80);

/* Just a little test message.  Go to http://192.168.4.1 in a web browser
   connected to this access point to see it.
*/

void handleRoot() {
  server.send(200, "text/html", "<h1>You are connected</h1>");
}

void setup() {
 
  // Setup LED pin
   pinMode(LED_BUILTIN, OUTPUT);
   digitalWrite(LED_BUILTIN, LOW);
   
  // Setup serial port
  Serial.begin(115200);
  Serial.println();
  
  // Begin WiFi
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  
  // Connecting to WiFi...
  Serial.print("Connecting to ");
  Serial.print(WIFI_SSID);
  // Loop continuously while WiFi is not connected
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(100);
    Serial.print(".");
  }
  
  // Connected to WiFi
  Serial.println();
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());

  
  // Begin Access Point
  Serial.println("Starting access point...");
  WiFi.softAPConfig(local_IP, gateway, subnet);
  WiFi.softAP(AP_SSID, AP_PASS, AP_CHANNEL, AP_HIDDEN, AP_MAX_CON);
  Serial.println(WiFi.localIP());

  // Connected to WiFi
  Serial.println();
  Serial.println("Connected!");
  Serial.print("IP address for network ");
  Serial.print(WIFI_SSID);
  Serial.print(" : ");
  Serial.println(WiFi.localIP());
  Serial.print("IP address for network ");
  Serial.print(AP_SSID);
  Serial.print(" : ");
  Serial.print(WiFi.softAPIP());
  Serial.print('\n');
 
  // Begin listening to UDP port
  UDP.begin(UDP_PORT);
  Serial.print("Listening on UDP port ");
  Serial.println(UDP_PORT);

  //
  server.on("/", handleRoot);
  server.begin();
  Serial.println("HTTP server started");
 
}
 
void loop() {
  server.handleClient();
  
   int packetSize = UDP.parsePacket();
   int atm =  UDP.read(packetBuffer, UDP_TX_PACKET_MAX_SIZE);
   Serial.println(atm);
   digitalWrite(LED_BUILTIN,LOW);
  if(packetSize && atm == 1)
  {
    Serial.print("Received packet of size ");
    Serial.println(packetSize);
    Serial.println(atm);
    digitalWrite(LED_BUILTIN,HIGH);
    
  }      
  delay(1000);
 
}
#2

your code looks fuzzy in my crystal ball ... (use </>)

#3

I added the server code now, it is outputing to the serial monitor

#4

I'd say that is standard debug output from the ESP. You may be able to change this in the board configuration. It would not bother me.

image

#5

is this the output from?

    int atm =  UDP.read(packetBuffer, UDP_TX_PACKET_MAX_SIZE);
    Serial.println(atm);