AsyncUDPServer receive message has a very long time delay #3816
Description
Hardware:
Board: ESP32 Dev Module
Core Installation/update date: 11/jul/2017
IDE name: Platform.io
Flash Frequency: 40Mhz
PSRAM enabled: no
Upload Speed: 115200
Computer OS: Mac OSX
Description:
I was trying to use two ESP32 communicate with each other, one is sending a UDP packet to another. But I observed a very long time delay from the server. And the delay is very unstable, it is about 10ms to several hundred ms. I want to build a remote controller using ESP32 wifi, this delay is unacceptable.
Two ESP32, one as an AP is the client, the other is a server with STA mode. The client send message to the server.
I use GPIO2 to output edge signal and oscilloscope to measure the delay between two devices.
Client.cpp
//Change the code below by your sketch
#include <WiFi.h>
#include <WiFiUdp.h>
#include <WiFiAP.h>
#include <Arduino.h>
const char *ssid = "ESP32";
const char *password = "password";
//IP address to send UDP data to:
// either use the ip address of the server or
// a network broadcast address
// const char * udpAddress = "192.168.4.2";
const char * udpAddress = "192.168.4.2";
const int udpPort = 1234;
//Are we currently connected?
uint8_t connected = false;
//The udp library class
WiFiUDP udp;
//wifi event handler
void WiFiEvent(WiFiEvent_t event){
switch(event) {
case SYSTEM_EVENT_STA_GOT_IP:
//When connected set
Serial.print("WiFi connected! IP address: ");
Serial.println(WiFi.localIP());
//initializes the UDP state
//This initializes the transfer buffer
udp.begin(WiFi.localIP(),udpPort);
connected = true;
break;
case SYSTEM_EVENT_STA_DISCONNECTED:
Serial.println("WiFi lost connection");
connected = false;
break;
default: break;
}
}
void connectToWiFi(const char * ssid, const char * pwd){
Serial.println("Connecting to WiFi network: " + String(ssid));
// delete old config
WiFi.disconnect(true);
//register event handler
WiFi.onEvent(WiFiEvent);
//Initiate connection
WiFi.begin(ssid, pwd);
Serial.println("Waiting for WIFI connection...");
}
void setup()
{
Serial.begin(115200);
pinMode(2, OUTPUT);
//Connect to the WiFi network
// connectToWiFi(ssid, password);
Serial.println();
Serial.println("Configuring access point...");
// You can remove the password parameter if you want the AP to be open.
WiFi.softAP(ssid, password);
IPAddress myIP = WiFi.softAPIP();
Serial.print("AP IP address: ");
Serial.println(myIP);
// connected = true;
}
const uint8_t message[5] = {0x31,0x32,0x33,0x34,0x35};
void loop()
{
delay(10);
connected = Serial.read();
//only send data when connected
if(connected == 0x30){
digitalWrite(2, HIGH);
//Send a packet
udp.beginPacket(udpAddress,udpPort);
udp.printf("Seconds since boot: %lu", millis());
udp.endPacket();
digitalWrite(2, LOW);
}
}Server.cpp
#include "WiFi.h"
#include "AsyncUDP.h"
const char *ssid = "ESP32";
const char *password = "password";
AsyncUDP udp;
unsigned long time_1, time_2, i = 0;
void onPacketCallBack(AsyncUDPPacket packet)
{
digitalWrite(2, HIGH);
if(i == 0) {
time_1 = millis();
i++;
Serial.printf("intervel is %d ms\n",time_1 - time_2);
}else if(i == 1) {
time_2 = millis();
i = 0;
Serial.printf("intervel is %d ms\n",time_2 - time_1);
}
// Serial.print("UDP Packet Type: ");
// Serial.print(packet.isBroadcast()?"Broadcast":packet.isMulticast()?"Multicast":"Unicast");
// Serial.print(", From: ");
// Serial.print(packet.remoteIP());
// Serial.print(":");
// Serial.print(packet.remotePort());
// Serial.print(", To: ");
// Serial.print(packet.localIP());
// Serial.print(":");
// Serial.print(packet.localPort());
// Serial.print(", Length: ");
// Serial.print(packet.length());
// Serial.print(", Data: ");
Serial.write(packet.data(), packet.length());
packet.flush();
Serial.println();
delay(1);
digitalWrite(2, LOW);
//reply to the client
// packet.printf("Got %u bytes of data", packet.length());
}
void setup()
{
Serial.begin(115200);
pinMode(2, OUTPUT);
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
if (WiFi.waitForConnectResult() != WL_CONNECTED) {
Serial.println("WiFi Failed");
while(1) {
delay(1000);
}
}
if(udp.listen(1234)) {
Serial.print("UDP Listening on IP: ");
Serial.println(WiFi.localIP());
udp.onPacket(onPacketCallBack);
}
}
void loop()
{
delay(1000);
//Send broadcast
// udp.broadcast("Anyone here?");
}