ESP8266 Community Forum

Hello,

I'm having trouble using any of the timers available to the ESP. I have tried the software timer described in the SDK documentation and the Ticker lib available for the Arduino IDE (which I assume uses the same functions) - both throw:



I have also tried multiple examples and short commands like prints to serial work fine, however functions that take longer to execute seem to trigger the hardware watchdog (is that what exception code 9 stands for?). What seems strange to me is that I have executed the exact same function in the main loop without any resets, so it seems logical to me that if it worked in main loop it should work in timed interrupts.

So I guess my question is if I am supposed to turn off the hardware wdt (is it even possible?) when executing the callback function, or is there something else I should be doing to run anything that takes more than 3ms to execute?

PS any information about the wdt would be appreciated

Maybe you should provide your code so that we can look for clues ...

Howdy Alex,
Re: Exception code 9

It means "LoadStoreAlignmentCause". I did some study on exception handling and how to debug and wrote that up in my book of notes ... see:

http://neilkolban.com/tech/esp8266/

And search in the book for "Exception".

Neil

I am fairly confident it's the same reasoning error that lots of people here make, because they're used to an mcu they have full control over and runs a single thread. The ex8266 isn't like that, your code must co-exist with code from the sdk and both need to run frequently to keep a.o. the wlan subsystem running.

So... Don't start a "main loop" from user_init, don't go doing all kinds of lengthy operations from an interrupt or timer callback. The watchdog will bark. Actually the watchdog is not your enemy. Some people go and try to defy or mislead the watchdog and learn it doesn't help. The watchdog is not the problem. Bad code is.

Rewrite your code so it never runs for an extended period of time. Do the preparations and "post" to your background task, which can finish the job. In the meantime the sdk code can run and do it's work. If the task is lengthy, break the loop, have the background task "post" to itself and continue the work when called again.

It's really just like an operating system with cooperative multitasking, where you can't hog the cpu as well. Think windows 3.1, it very much resembles that concept.