[2.0.2] softAP unstable when performing a WiFi.scanNetworks() - Windows 10 clients get disconnected. #4554
Description
Hardware:
Board: ESP32 Dev Module
Core Installation version: 1.0.4 and 1.0.5 RC1/RC2
IDE name: Platform.io
Flash Frequency: 40Mhz
PSRAM enabled: no
Upload Speed: 115200
Computer OS: Windows 10 and Android 9
Description:
softAP gets unstable when performing a wifi scan in latest 1.0.5 RC1 and RC2. In version 1.0.4 this can be done without problems. On 1.0.5 RC1/RC2 the AP goes down while scanning. This happens when I'm connected to the AP with a PC with Windows 10 (I tried two different laptops with Windows 10 and both have the same problem). Curiously, on two Android phones this worked on both versions.
Sketch:
The following is the WiFi AP example with minor modifications for showing scan results. This code compiled against 1.0.4 works perfectly but compiled against 1.0.5 RC1/RC2 does not work. For compiling I use PlatformIO but this issue happens also with Arduino IDE.
#include <WiFi.h>
#include <WiFiClient.h>
#include <WiFiAP.h>
#define LED_BUILTIN 2 // Set the GPIO pin where you connected your test LED or comment this line out if your dev board has a built-in LED
// Set these to your desired credentials.
const char *ssid = "helloworld";
const char *password = "";
WiFiServer server(80);
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
Serial.begin(115200);
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);
server.begin();
Serial.println("Server started");
}
void loop() {
WiFiClient client = server.available(); // listen for incoming clients
if (client) { // if you get a client,
Serial.println("New Client."); // print a message out the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected()) { // loop while the client's connected
if (client.available()) { // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println();
// the content of the HTTP response follows the header:
client.print("Starting scan now<br>");
uint8_t numSsid = WiFi.scanNetworks(); // Scanning Networks
client.printf("Number of available WiFi networks discovered: %d <br>", numSsid);
for (int i = 0; i < numSsid; i++) {
client.printf("%d: %s, Ch:%d (%ddBm) <br>", i + 1, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i));
}
// The HTTP response ends with another blank line:
client.println();
// break out of the while loop:
break;
} else { // if you got a newline, then clear currentLine:
currentLine = "";
}
} else if (c != '\r') { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
}
}
// close the connection:
client.stop();
Serial.println("Client Disconnected.");
}
}
Debug Messages:
No error message. The PC gets disconnected and does not receive the rest of the webpage (the scan results).