I have need of the pulse counter in a current ESP32 project and, not seeing any maintained implementations, have gone ahead and rolled another. Sorry.

Since there doesn't seem to be much movement on the idea of exposing the IDF functions through dynamic linking, I've just added it as a straight-C extension of the machine module in the ESP32 port. I started copying your API from #5496, @tve, but then took a slightly different tack when I realised that I couldn't figure out how to support all of the features of the ESP32 PCNT peripheral with it.

So I have gone for this in the simple case:

from machine import Counter, Pin

counter = Counter(0, pin=Pin(12, Pin.IN), rising=Counter.INCREMENT)
counter.start()
count = counter.value()

This looks like it ought to work OK as an API for other ports. However, using rising= and falling= instead of edge= allows for both to be specified, which means the extended functionality of the ESP32 PCNT peripheral can be used to do easy 1X decoding of a quadrature rotary encoder:

from machine import Counter, Pin

pin_a = Pin(12, Pin.IN, pull=Pin.PULL_UP)
pin_b = Pin(14, Pin.IN, pull=Pin.PULL_UP)
counter = Counter(0, pin=pin_a, rising=Counter.DECREMENT, falling=Counter.INCREMENT,
                     mode_pin=pin_b, mode_high=Counter.NORMAL, mode_low=Counter.HOLD)
counter.start()
count = counter.value()

Or use mode_low=Counter.REVERSE to do 2X decoding. In fact, this implementation also supports calling the .init() method with an additional channel=1 keyword argument to configure the second channel of the PCNT, allowing for 4X decoding on a single PCNT unit.

It also supports filter= to set the short pulse filter, minimum= and maximum= for setting counter limits, threshold0= and threshold1= for setting threshold event levels and all of the PCNT events (IRQ_ZERO, IRQ_MINIMUM, IRQ_MAXIMUM, IRQ_THRESHOLD0 and IRQ_THRESHOLD1) via the .irq(trigger=, handler=) method.

I've not written any documentation for it yet I'm afraid. It's sitting in draft PR #7582 if anyone is interested in looking at it. Like I say, my primary reason for doing this is that I need it more than that I'm interested in seeing it through to mainline. I don't have any hardware for the other MicroPython architectures to work on an implementation of Counter for them.

Uh oh!

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