ESP8266 Community Forum

- Tue Dec 01, 2015 11:13 am #35453 Hi,

I have a pretty weird UDP issue.

My setup is as follows :
- ESP8266 as SoftAP and UDP client
- ESP8266 sending an UDP broadcast packet every 2s.
- Android application connected as Wi-Fi Station and acting as an UDP Server

I'm able to sniff all the UDP packets in the air using another PC running wireshark and clearly see them on a regular 2s frequency.

On my Android app, I only receive packets once in a while in a kind of weird random fashion (I know UDP is not guaranteed - but doing tests in 'clean' air). I know my android application works as I have tested it with some other UDP clients.

I also have an older setup running the same Arduino software but using a Wi-Fi router and an W5100 ethernet controller (just changing from WiFiUdp to EthernetUDP). I don't have the issue with that setup.

I'm running out of ideas of what can be the root cause of this....

Below my code snippet, if anyone would see something wrong :

Code: Select all#include <ESP8266WiFi.h>
#include <WiFiUdp.h>


const char* ssid = "PyRC Timing";
WiFiUDP udp;
IPAddress   broadcastAddress(255,255,255, 255);

unsigned char udpBuffer[10];
long cnt = 0;


void setup() {

  pinMode(16, OUTPUT);
 
  Serial.begin(921000);
  while (!Serial);
 
  // Connect to WiFi network
  Serial.println();
  Serial.println("Setting up SoftAP");
 
  Serial.setDebugOutput(false);
  WiFi.mode(WIFI_AP);
  WiFi.softAP(ssid);
 
  IPAddress softAPIP = WiFi.softAPIP();
  Serial.print("IP address: ");
  Serial.println(softAPIP);
  Serial.println();

  Serial.println("Server started");

  udp.begin(4445);

 

}

void loop() {
    digitalWrite(16, HIGH);
    delay(1000);
   
     int volt = 500;
     long timeStamp = millis();
     
    udpBuffer[0] = (byte) (volt & 0xFF);
    udpBuffer[1] = (byte)((volt >> 8) & 0xFF);
    udpBuffer[2] = '-';
    udpBuffer[6] = (byte) (timeStamp & 0xFF);
    udpBuffer[5] = (byte)((timeStamp >> 8) & 0xFF);
    udpBuffer[4] = (byte)((timeStamp >> 16) & 0xFF);
    udpBuffer[3] = (byte)((timeStamp >> 24) & 0xFF);
    udpBuffer[7] = ';';

   udp.beginPacket(broadcastAddress, 4445);
   udp.write(udpBuffer, 8);
   udp.endPacket();

   Serial.print("Sent packet : ");
   Serial.println(cnt++);

 
 digitalWrite(16, LOW);
 delay(1000);
 
}