Learning the Teensy LC: Interrupt Service Routines

Custom ISR in the Teensy LC

As a follow-on to my PWM experiments, I wanted to create a custom interrupt service routine (ISR) in the Teensy LC. This would be similar to using the ISR() macro in an ATmega-based Arduino. Because the ARM has different vectors (and some other weird/cool things, like configurable interrupt priority levels), I knew the normal ATmega vectors would not work. Luckily, PJRC created a set of vectors to work with the Teensy, which can be found in this code.

You don’t need any additional components for this example. We are just going to flash the on-board LED using our custom ISR. The LED will flash a few times for a second and then pause (on or off) for a second. We accomplish this by enabling and disabling the ISR every second in loop().


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