esp8266/Arduino

A WDT reset problem can be created using the example program ESP8266WebServer/HelloServer with periodic calls to noInterrupts(). The same program works correctly when built with 1.6.4-673-g8cd3697.

Modify the example program to add SSID/PSK. Verify it connects. Ping the ESP server using sudo ping -A <ESP IP addr>. This sends about 1000 pings/sec which the ESP handles correctly. My test was done using a package built from git commit aafacdcb.

Next modify the loop() function to add noInterrupts(). The idea for this was derived from a program that updates WS281x/NeoPixel LEDs from network packets received at 30 updates/sec. The LED code has been removed since it was discovered on the NeoPixelBus repo chat that the key factor is disabling interrupts with lots of WiFi traffic.

uint32_t lastTime = 0;

void loop()
{
  server.handleClient();

  // Every 30 ms, disable interupts
  if ((millis() - lastTime) > 30) {
    //uint32_t savedPS;
    lastTime = millis();
    //savedPS = xt_rsil(15);  // does not work either
    noInterrupts();
    delayMicroseconds(2000);
    interrupts();
    //xt_wsr_ps(savedPS);
    Serial.println(lastTime);
  }
}

After downloading the modified example code, do sudo ping -A <ESP IP addr>. On my system this results in WDT reset less than 10 seconds. The rate of pings can be reduced with various ping options but the WDT reset still occurs but less frequently.

Removing noInterrupts/interrupts eliminates the WDT reset but bit banging the WS281x LED protocol requires interrupts off. However, this demonstrates the problem is caused by disabling interrupts and not the addition of 2 ms delay to loop().

After putting the noInterrupts/interrupts back in, build with 1.6.4-673-g8cd3697. On my system, the WDT resets do not occur even when handling 1000 pings/sec for 10 minutes.