Hi, I'm having a problem understanding what is happening when it comes to detecting when an ISR has changed a global variable. I wrote the little program below and I'm seeing some different behaviors. Of the four test functions below only number two works as desired. The others appear to be hang…

Interrupts and Global Variable Access

mjward August 25, 2016, 4:42pm 2

Hi,

Haven't studied your code carefully, but a quick glance suggests you should declare "counter" volatile:
https://www.arduino.cc/en/Reference/Volatile
best,
Michael

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