MicroPython infrared remote codes on GPIO 15, on an ESP32-DevKitC V4

# Infrared remote: press a button on the remote and its code is
# printed. The receiver's output is on GPIO 15 with a 10k pull-up.
from nec import NEC
import time

remote = NEC(15)
print("Point the remote and press a button")

while True:
    code = remote.read()
    if code is not None:
        print("0x%06x" % code)
    time.sleep_ms(20)

# nec.py: read an NEC infrared remote through a VS1838B-style receiver.
# The receiver's output idles high and goes low during each burst. A
# frame is a 9 ms burst, a 4.5 ms gap, then 32 bits, least significant
# first: a bit is a short burst and a short gap (0) or a long gap (1).
from machine import Pin
import time

class NEC:
    def __init__(self, gpio):
        self.pin = Pin(gpio, Pin.IN)
        self.edges = []
        self.last = 0
        self.code = None
        self.pin.irq(trigger=Pin.IRQ_FALLING, handler=self._edge)

    def _edge(self, pin):
        now = time.ticks_us()
        gap = time.ticks_diff(now, self.last)
        self.last = now
        if gap > 20000:                # a long quiet: a new frame starts
            self.edges = []
            return
        self.edges.append(gap)
        if len(self.edges) == 33:      # the header and 32 bits
            bits = 0
            for i, t in enumerate(self.edges[1:]):
                if t > 1700:           # 2.25 ms between edges is a 1
                    bits |= 1 << i
            self.code = bits
            self.edges = []

    def read(self):
        """The last frame as 0xff then the address and command, MSB first, or None."""
        bits, self.code = self.code, None
        if bits is None:
            return None
        command = (bits >> 16) & 0xff
        if command ^ ((bits >> 24) & 0xff) != 0xff:
            return None                 # the command and its inverse disagree
        # the way most tutorials print it: each byte bit-reversed, 0xff first
        return 0xff0000 | _reverse(command) << 8 | _reverse(command ^ 0xff)


def _reverse(byte):
    out = 0
    for i in range(8):
        out = out << 1 | (byte >> i) & 1
    return out