Python scripts publishing MQTT sensor data

Comments

• Laura

  May 2020

  On our side we've used a bit of the internal python tools but we don't have any sample code or tips: https://github.com/aws/aws-iot-device-sdk-python
• DJC_2

  May 2020 edited May 2020

  Nothing too elegant, but working

  # usage: python stream_acc.py [mac1] [mac2] ... [mac(n)]
  from __future__ import print_function
  from mbientlab.metawear import MetaWear, libmetawear, parse_value,create_voidp_int,create_voidp
  from mbientlab.metawear.cbindings import *
  from time import sleep
  from threading import Event
  import platform
  import sys
  import paho.mqtt.publish as publish
  
  MQTT_SERVER = "xx.xx.xx.xx" #IP or Name of MQTT Broker
  MQTT_PATH = "test_channel"
  
  if sys.version_info[0] == 2:
      range = xrange
  
  class State:
      def __init__(self, device):
          self.device = device
          self.samples = 0
          self.callback = FnVoid_VoidP_DataP(self.data_handler)
  
  def data_handler(self, ctx, data):
          # Only publish message if signal eclipses set value
          if parse_value(data) > 5000: 
              print("%s -> %s" % (self.device.address, parse_value(data)))
              publish.single(MQTT_PATH, parse_value(data), hostname=MQTT_SERVER)
              self.samples+= 1
          else:
              print("%s -> %s" % (self.device.address, parse_value(data)))
              self.samples+= 1
  
  e = Event()
  states = []
  
  for i in range(len(sys.argv) - 1):
          d = MetaWear(sys.argv[i + 1])
          d.connect()
          print("Connected to " + d.address)
          states.append(State(d))
  
  for s in states:
          print("Configuring device")
          libmetawear.mbl_mw_settings_set_connection_parameters(s.device.board, 7.5, 7.5, 0, 6000)
          sleep(1.5)
  
  # Get Signal
  adc_signal = libmetawear.mbl_mw_gpio_get_analog_input_data_signal(s.device.board,0,GpioAnalogReadMode.ADC)
  
  # Subscribe
  libmetawear.mbl_mw_datasignal_subscribe(adc_signal, None, s.callback) 
  
  # Create Timer
  timer = create_voidp(lambda fn: libmetawear.mbl_mw_timer_create_indefinite(s.device.board, 50, 0, None, fn), resource = "timer", event = e)
  
  # Start recording commands:
  libmetawear.mbl_mw_event_record_commands(timer)
  
  # The first command is to read the signal - temp data - based on the timer - every 1s
  libmetawear.mbl_mw_datasignal_read(adc_signal)
  
  # Stop recording commands
  create_voidp_int(lambda fn: libmetawear.mbl_mw_event_end_record(timer, None, fn), event = e)
  
  # Start the timer
  libmetawear.mbl_mw_timer_start(timer)
  
  sleep(60.0)
  
• Laura

  May 2020 edited May 2020

  Nice.