IR Transceiver for STEMMA_IR_Transceiver_Examples CircuitPython throws errors

[EAGrahamJr]

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As written, the transceiver seems to have developed a feedback loop wherein the receiver is actually also receiving the transmitted code, which then re-transmits, etc. until a bit is dropped and the decode fails.

If the example code is modified as below, there are no errors and the receive/transmit functions seem to work as expected (on a lab bench).

# SPDX-FileCopyrightText: 2024 Liz Clark for Adafruit Industries
# SPDX-License-Identifier: MIT

import time
import array
import pulseio
import board
import adafruit_irremote

# Create a 'PulseOut' to send infrared signals on the IR transmitter @ 38KHz
pulseout = pulseio.PulseOut(board.SCL1, frequency=38000, duty_cycle=2**15)
# Create an encoder that will take numbers and turn them into NEC IR pulses
encoder = adafruit_irremote.GenericTransmit(header=[9000, 4500],
                                            one=[560, 1700],
                                            zero=[560, 560],
                                            trail=0)
# IR receiver setup
ir_receiver = pulseio.PulseIn(board.SDA1, maxlen=120, idle_state=True)
decoder = adafruit_irremote.GenericDecode()

skip_next = False
while True:
    pulses = decoder.read_pulses(ir_receiver)
    try:
        if not skip_next:
            # Attempt to decode the received pulses
            received_code = decoder.decode_bits(pulses)
            if received_code:
                hex_code = ''.join(["%02X" % x for x in received_code])
                print(f"Received: {hex_code}")
                # Convert pulses to an array of type 'H' (unsigned short)
                pulse_array = array.array('H', pulses)
                # send code back using original pulses
                pulseout.send(pulse_array)
                print(f"Sent: {pulse_array}")
                skip_next = True
        else:
            skip_next = False
    except adafruit_irremote.IRNECRepeatException:  # Signal was repeated, ignore
        pass
    except adafruit_irremote.IRDecodeException:  # Failed to decode signal
        print("Error decoding")
    ir_receiver.clear()  # Clear the receiver buffer
    time.sleep(1)  # Delay to allow the receiver to settle
    print()

Note that if the read and write functions are "decoupled" (e.g. record and playback), the device works as each of the counterparts.