Adding edge-sensitive transition detection to GPIO devices:
Although many GPIO devices can detect the rising and falling edge of a signal-level change, some applications only need to capture the leading edge and not monitor the falling edge. These GPIO devices can be enhanced to detect edge-sensitive signal transitions. A simple circuit provides the transition detection.
This one-shot circuit is one of the simple logic tricks that can be achieved with a Schmitt trigger, more can be found there:
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