A simple slider subscriber plus raw data publish

pubSub_example.py

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+# The MIT License (MIT)
+# Copyright (c) 2018 Mike Teachman
+# https://opensource.org/licenses/MIT
+#
+# Example MicroPython and CircuitPython code showing how to use the MQTT protocol with Adafruit IO, to  
+# publish and subscribe on the same device
+#
+# Tested using the releases:
+#   ESP8266
+#       MicroPython 1.9.3
+#       MicroPython 1.9.4
+#       CircuitPython 2.3.1     (needs addition of CircuitPython specific umqtt module)
+#       CircuitPython 3.0.0     (needs addition of CircuitPython specific umqtt module)
+#   ESP32
+#       MicroPython 1.9.4       (needs addition of MicroPython umqtt module)
+#
+# Tested using the following boards:
+#   Adafruit Feather HUZZAH ESP8266
+#   Adafruit Feather HUZZAH ESP32
+#   WeMos D1 Mini
+#
+# User configuration parameters are indicated with "ENTER_".  
+
+import network
+import time
+from umqtt.robust import MQTTClient
+import os
+import gc
+import sys
+from machine import Pin,ADC,PWM
+
+#pin = Pin(2, Pin.OUT, value = 1)
+adc = ADC(0)
+pwm = PWM(Pin(2))
+
+def cb_03(topic, msg):	
+	pwm.duty(int(msg))
+
+# WiFi connection information
+WIFI_SSID = 'LG'
+WIFI_PASSWORD = 'lg123456'
+
+# turn off the WiFi Access Point
+ap_if = network.WLAN(network.AP_IF)
+ap_if.active(False)
+
+# connect the device device to the WiFi network
+wifi = network.WLAN(network.STA_IF)
+wifi.active(True)
+wifi.connect(WIFI_SSID, WIFI_PASSWORD)
+
+# wait until the device is connected to the WiFi network
+MAX_ATTEMPTS = 20
+attempt_count = 0
+while not wifi.isconnected() and attempt_count < MAX_ATTEMPTS:
+    attempt_count += 1
+    time.sleep(1)
+
+if attempt_count == MAX_ATTEMPTS:
+    print('could not connect to the WiFi network')
+    sys.exit()
+
+# create a random MQTT clientID 
+random_num = int.from_bytes(os.urandom(3), 'little')
+mqtt_client_id = bytes('client_'+str(random_num), 'utf-8')
+
+# connect to Adafruit IO MQTT broker using unsecure TCP (port 1883)
+# 
+# To use a secure connection (encrypted) with TLS: 
+#   set MQTTClient initializer parameter to "ssl=True"
+#   Caveat: a secure connection uses about 9k bytes of the heap
+#         (about 1/4 of the micropython heap on the ESP8266 platform)
+ADAFRUIT_IO_URL = b'io.adafruit.com' 
+ADAFRUIT_USERNAME = b'icreate'
+ADAFRUIT_IO_KEY = b'697847b8dfbb4b43b8f06bf7ed037887'
+#ADAFRUIT_IO_FEEDNAME_01 = b'freeHeap'
+ADAFRUIT_IO_FEEDNAME_02 = b'ambient-light'
+ADAFRUIT_IO_FEEDNAME_03 = b'onboard-led'
+
+client = MQTTClient(client_id=mqtt_client_id, 
+                    server=ADAFRUIT_IO_URL, 
+                    user=ADAFRUIT_USERNAME, 
+                    password=ADAFRUIT_IO_KEY,
+                    ssl=False)
+
+try:            
+    client.connect()
+except Exception as e:
+    print('could not connect to MQTT server {}{}'.format(type(e).__name__, e))
+    sys.exit()
+
+# publish free heap statistics to Adafruit IO using MQTT
+# subscribe to the same feed
+#
+# format of feed name:  
+#   "ADAFRUIT_USERNAME/feeds/ADAFRUIT_IO_FEEDNAME"
+#mqtt_feedname_01 = bytes('{:s}/feeds/{:s}'.format(ADAFRUIT_USERNAME, ADAFRUIT_IO_FEEDNAME_01), 'utf-8')
+mqtt_feedname_02 = bytes('{:s}/feeds/{:s}'.format(ADAFRUIT_USERNAME, ADAFRUIT_IO_FEEDNAME_02), 'utf-8')
+mqtt_feedname_03 = bytes('{:s}/feeds/{:s}'.format(ADAFRUIT_USERNAME, ADAFRUIT_IO_FEEDNAME_03), 'utf-8')
+
+#client.set_callback(cb_01)
+#client.set_callback(cb_02)
+client.set_callback(cb_03)
+
+#client.subscribe(mqtt_feedname_01)
+#client.subscribe(mqtt_feedname_02)
+client.subscribe(mqtt_feedname_03)
+
+PUBLISH_PERIOD_IN_SEC = 3 
+SUBSCRIBE_CHECK_PERIOD_IN_SEC = 0.5 
+accum_time = 0
+
+while True:
+
+    try:
+        # Publish
+        if accum_time >= PUBLISH_PERIOD_IN_SEC:
+            free_heap_in_bytes = gc.mem_free()
+            print('Publish:  rawPot = {}'.format(adc.read()))
+            client.publish(mqtt_feedname_02,    
+                           bytes(str(adc.read()), 'utf-8'), 
+                           qos=0)
+			#client.publish(mqtt_feedname_03, f(y))    
+            #               bytes(str(free_heap_in_bytes), 'utf-8'), 
+            #               qos=0)
+            accum_time = 0                
+
+
+        # Subscribe.  Non-blocking check for a new message.  
+        client.check_msg()
+
+        time.sleep(SUBSCRIBE_CHECK_PERIOD_IN_SEC)
+        accum_time += SUBSCRIBE_CHECK_PERIOD_IN_SEC
+
+    except KeyboardInterrupt:
+        print('Ctrl-C pressed...exiting')
+        client.disconnect()
+        sys.exit()