Does anybody know what is the shortest pulse width that the Raspberry Pi (any model) GPIO interrupt pins can detect? I have a project in mind, but the pulses would be between 5 & 17ns wide.
The GPIO peripheral is identical on all Pi models. The only difference is in the number of GPIO routed to the expansion header.
The Pi has a
GPIO Asynchronous rising/falling Edge Detect mode.
See pages 99/100 of BCM2835 ARM Peripherals.
"Asynchronous means the incoming signal is not sampled by the system clock. As such rising/falling edges of very short duration can be detected."
I'm fairly sure that 4ns will be detected.
I don't know if this mode is the Pi default. You will have to experiment.