Python scripts publishing MQTT sensor data

DJC_2

I have MetaC running with Python script streaming analog data from GPIO

I would like to extend to have MQTT message published when signal eclipses a set threshold.

Just curious if anyone has done before, sample code or tips for implementing.

Thanks

Laura

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

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

Nice.