Controls when temperature and weight are measured, and inputs measurements into local mongo instance.

worker_runner.py

#!/usr/bin/python
from pymongo import MongoClient
import Adafruit_MCP3008
import Adafruit_DHT
import time

'''
Weight
'''
CLK = 2
MISO = 3
MOSI = 4
CS = 17
mcp = Adafruit_MCP3008.MCP3008(clk=CLK, cs=CS, miso=MISO, mosi=MOSI)


def measureWeight():
    '''
    Measures weight.
    @return the weight, in pounds.
    '''
    def weight(x):
        '''
        Converts ADC reading into pounds.
        '''
        x = int(x)
        
        # The results of 3 polynomial regressions, on 3 data sets, averaged.
        a = 1E-8 * x**4 - 1E-5 * x**3 + 0.0036 * x**2 - 0.1661 * x + 1.5569
        b = 1E-8 * x**4 - 7E-6 * x**3 + 0.0007 * x**2 + 0.2831 * x - 6.8611
        c = 2E-9 * x**4 - 2E-6 * x**3 + 0.0004 * x**2 + 0.2194 * x - 6.515

        return (a + b + c) / 3

    count = 0
    average = 0

    
    # Compensate for remaining signal flutter.
    while count < 10:
        values = mcp.read_adc(0)

        count += 1
        average += values

        time.sleep(0.01)

    average /= 10
    value = int(weight(average))

    return value if value >= 0 else 0


'''
Temperature
'''
sensor = Adafruit_DHT.DHT11


def measureTemperature():
    '''
    Measures temperature and humidity
    @return A list of lists, where the latter are [temperature, humidity] for
            each sensor.
    '''
    pins = [10, 25, 20, 21]
    readings = [[None, None], [None, None], [None, None], [None, None]]

    for i in range(0, len(readings)):
        readings[i][0], readings[i][1] = Adafruit_DHT.read_retry(sensor,
                                                                 pins[i])

    return readings


db = MongoClient().sensorData  # Establish db connection, fetch sensorData db.
data = db.data                 # Create or access a collection called data.
hiveInfo = db.hiveInfo

while True:
    tempReading = measureTemperature()
    temp = [x[0] for x in tempReading if x is not None]
    hum = [x[1] for x in tempReading if x is not None]
    position = [44, 44] # Start in the center (N.B.: edges are 10 and 80).

    # Set hive cluster position, according to temperature readings.
    if temp[0] is temp[1]:
        position[0] = 44
    elif temp[0] > temp[1]:
        position[0] = 10
    else:
        position[0] = 80

    if temp[2] is temp[3]:
        position[1] = 44
    elif temp[2] > temp[3]:
        position[1] = 10
    else:
        position[1] = 80

    # Update mongo.
    reading = {
        'weight': measureWeight(),
        'temperature': sum(temp) / len(temp),
        'population': hiveInfo.find_one()['population'],
        'date': int(time.time()),
        'humidity': sum(hum) / len(hum),
        'position': position,
        'uploaded': False # Is this datum present on Firebase?
    }

    data.insert_one(reading)
    time.sleep(5)