ESP8266 Community Forum

Hello, I want to do a MQTT client.publish(topic,msg); on my ESP07 in Arduino language inside an ISR.

When the publish is executing I got an Exception 9 and a stack-dump.

void ISR() // Interrupt-Service-Routine
{
client.publish("button", "1"); // Publish topic "button" with message "1"
}

When I test the publish line outside the ISR it works without any problem.
Also when I replace the client.plublish with something else like a Serial.print("hello."); there is no stack-dump.

Who knows a solution for this problem.

Regards, Wim

It crashes because you shouldn't do IO inside an ISR. Instead have the ISR just set a flag to indicate the event has happened and check that flag in the main loop to see if it should do the publish.

Thanks for the quick answer but why does a Serial.print work inside the ISR?

paysan wrote:Thanks for the quick answer but why does a Serial.print work inside the ISR?

And if I use the "flag" methode in the ISR there is no need to use the interrupt system.
If I need to check the flag in the mainloop I can check the button also in the mainloop straight away.