code.py

import os
import time
import binascii
import ssl
import wifi
import socketpool
import adafruit_connection_manager
import adafruit_minimqtt.adafruit_minimqtt as MQTT

use_adafruit_io=False

input_feed=os.getenv('input_feed')
output_feed=os.getenv('output_feed')
ssid=os.getenv('CIRCUITPY_WIFI_SSID')
ssid_pw=os.getenv('CIRCUITPY_WIFI_PASSWORD')
broker=os.getenv('aio_broker') if use_adafruit_io else os.getenv('mqtt_broker')
port=int(os.getenv('aio_port')) if use_adafruit_io else os.getenv('mqtt_port')
username=os.getenv('aio_username') if use_adafruit_io else os.getenv('mqtt_user')
password=os.getenv('aio_key') if use_adafruit_io else os.getenv('mqtt_password')

## DEBUG CODE
print(f"input_feed: {input_feed}")
print(f"output_feed: {output_feed}")
print(f"ssid: {ssid}")
print(f"broker: {broker}")
print(f"port: {port}")
print(f"username: {username}")

## WiFi setup
print(f"Connecting to SSID {ssid}")
wifi.radio.connect(ssid, ssid_pw)
print(f"Connected to SSID {ssid}")
sockpool=socketpool.SocketPool(wifi.radio)
ssl_context=ssl.create_default_context()

# Initialize a new MQTT Client object
mqtt_client = MQTT.MQTT(
    broker=broker,
    port=port,
    username=username,
    password=password,
    socket_pool=sockpool,
    ssl_context=ssl_context,
    use_binary_mode=True,
)
print("Connecting to the MQTT broker...")
mqtt_client.connect(True)
print(f"Maximum MQTT payload size is: ", mqtt_client.mqtt_msg)

def generate_payload():
    # Generate 13KB of ASCII text using repeated 'A'
    payload_size_kb = 2.834
    payload = "A" * int(payload_size_kb * 1024)  # 1KB = 1024 bytes
    return payload

# Snap a photo and publish it to the broker
def send_payload():
    mqtt_client.publish(output_feed, generate_payload())

## Main Loop
while True:
    # Take a photo
    try:
        send_payload()
    except MemoryError as e:
        print("Exception: ", e)
        pass

    # Last!
    time.sleep(1)