The problem testing my mood for the past few days is that although my ESP8266 chip is perfectly capable of fetching packets with parsePacket in a while loop, it completely misses these when I want BOTH to listen to incoming packets, but also allow my ESP8266 to read out sensors and send these over wifi.
So I cut out everything that has to do with the sensors and pasted the code below, but here is what's happening.
MY PROBLEM IS THIS STEP:
My guess is that A. works fine because the 'while' condition will allow parsePacket to always catch an incoming packet. And because B. is inside the void loop I cannot use a 'while' condition but instead an 'if' statement, the parsePacket command is not requesting for an incoming package on the right moment. I have not been able to implement something that solves this. Quite a bit of searching is not really helping out and I cannot imagine I am alone having this problem.
Some things I found related:
I greatly appreciate your help and feedback!
Here is my code:
#include <Wire.h>
#include <ESP8266WiFi.h>
#include <WiFiUDP.h>
String SendString;
String SendBuffer = "STR ";
boolean SendSuccessful;
char SendChar[32];
// wifi connection variables
const char* password = #########;
boolean wifiConnected = false;
String ssid_string;
char ssid[10];
// UDP variables
unsigned int localPort = 8888;
WiFiUDP UDP;
boolean udpConnected = false;
char packetBuffer[UDP_TX_PACKET_MAX_SIZE]; //buffer to hold incoming packet,
char ReplyBuffer[500] = "acknowledged"; // a string to send back
void setup(void) {
Serial.begin(115200);
//Setup all my sensors, code not relevant
//Connect Wifi
ssid_string = "DRILL_" + String(chip_id);
ssid_string.toCharArray(ssid, 500);
SetupWifi(ssid);
}
void loop(void) {
//B. <<<< SO THIS IS THE PART IN THE LOOP THAT IS NOT WORKING
int packetSize = UDP.parsePacket();
packetSize = UDP.parsePacket();
if (packetSize) {
Serial.println("");
Serial.print("Received packet");
// read the packet into packetBufffer
UDP.read(packetBuffer, UDP_TX_PACKET_MAX_SIZE);
Serial.println("Contents:");
int value = packetBuffer[0] * 256 + packetBuffer[1];
Serial.println(value);
}
//Read out all my sensors, code not relevant, paste all sensor data in one string
//SendString over serial
Serial.print(SendString);
SendIntervalUDP(1); // Send SendString over UDP every x measurements (see function below)
//Listen to serial
if (Serial.available() > 0) {
String Received = Serial.readString();
Serial.println("ESP received: " + Received);
}
}
Now this are some of the support functions in setting up the wifi and sending data over wifi
unsigned long previousWifiStatMillis;
//Connect wifi during setup
void SetupWifi(char my_ssid[]) {
// WiFi init
wifiConnected = createAP(my_ssid);
udpConnected = connectUDP();
// Wait for first packet
Serial.println("Waiting for start");
//A. <<<< SO THIS IS THE PART IN THE CODE THAT IS ACTUALLY WORKING
int packetSize = UDP.parsePacket();
while (packetSize < 1) {
packetSize = UDP.parsePacket();
yield(); // Allow the background functions to work
//Listen to serial
if (Serial.available() > 0) {
String Received = Serial.readString();
Serial.println("I received: " + Received);
if (Received.substring(0) == "S") {
Serial.println("Starting..");
break;
}
}
if (packetSize)
{
Serial.println("");
Serial.print("Received packet");
// read the packet into packetBufffer
UDP.read(packetBuffer, UDP_TX_PACKET_MAX_SIZE);
Serial.println("Contents:");
int value = packetBuffer[0] * 256 + packetBuffer[1];
Serial.println(value);
}
}
}
// connect to UDP – returns true if successful or false if not
boolean connectUDP() {
boolean state = false;
Serial.println("");
Serial.println("Connecting to UDP");
if (UDP.begin(localPort) == 1) {
Serial.println("Connection successful");
state = true;
}
else {
Serial.println("Connection failed");
}
return state;
}
// connect to wifi – returns true if successful or false if not
boolean createAP(char my_ssid[]) {
boolean state = true;
int i = 0;
WiFi.softAP(my_ssid, password); // Start the access point
WiFi.mode(WIFI_AP);
Serial.print("Access Point \"");
Serial.print(my_ssid);
Serial.println("\" started");
Serial.print("IP address:\t");
Serial.println(WiFi.softAPIP()); // Send the IP address of the ESP8266 to the computer
state = true;
return state;
}
// connect to wifi – returns true if successful or false if not
boolean connectWifi(char my_ssid[]) {
boolean state = true;
int i = 0;
WiFi.begin(my_ssid, password);
Serial.println("");
Serial.println("Connecting to WiFi");
// Wait for connection
Serial.print("Connecting");
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
if (i > 20) {
state = false;
break;
}
i++;
}
if (state) {
Serial.println("");
Serial.print("Connected to ");
Serial.println(my_ssid);
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
}
else {
Serial.println("");
Serial.println("Connection failed.");
}
return state;
}
void SendIntervalUDP(int interval) {
//Send an udp packet every x packets with x the interval
j++;
if (j > (interval-1) ) {
j = 0;
//SendString over wifi
if (wifiConnected) {
if (udpConnected) {
// send a reply, to predetermined hotspot
UDP.beginPacket(UDP.remoteIP(), UDP.remotePort());
SendBuffer.toCharArray(ReplyBuffer, 500);
UDP.write(ReplyBuffer);
UDP.endPacket();
}
}
SendBuffer = "";
}
}
The WiFi events in "Generic Class" are for OSI levels below transport layer. TCP and UDP are transport layer.
To receive UDP packets you must call UDP.parsePacket(); in loop() (or in a function called from loop()) like with every other Arduino networking library implementing the Arduino UDP base class.
If packet is available call to parsePacket reads the packet into internal buffer and returns the size of the packet. Next call to parsePacket clears the buffer and fills it with new packet if it is available. You call parsePacket twice and the second always returns nothing.