**Tutorial on how to count warmwater consuption with temperature sensor**

Peter Cordova
pc222hf

In this project I try to count my monthly warmwater consuption with detailed costs. I use temperature sensor and Pycom device to send data to Pybytes plattform that gather information and visualize it in charts.

It takes about 5 hours to set-up everything and about 5-10 minutes a day for maintenance.

**Objective**

I chose this project because i was curious about finding out speific warmwater costs. Every month I get a invoice for warm water that is around 450sek. I just get amount without any specifications. Then I was intrested to find out how costs are devided and asigned. Thats why I decided to create a device that count my warmwater consuption during the day. I think this information is usefull to know for both invironment and better private economy.

**Material**

I used following material:

| Material | Purpose |
| -------- | -------- |
| Pycom ExtansionBoard | connection and power
Lopy4|network and programming
Lora Anthena|network
USB cable|power supply
sensor DHT11|measure temperature

I bought the material on Electrokit.se and I paid 995SEK for a set. I got all I needed plus other sensors that I didnt use.
 ExtansionBoard and Lopy4
Lora Anthena
 DHT11 Temperature and Humidity sensor

**Computer setup**

I installed and used Atom as IDE and Pymakr plugins.
I uploaded all the code through the Atom and used Pybytes plattform to get the data. I followed Pybytes tutorials for setting Wifi and Lora connections.

**Putting everything together**

I started with connection of my Lopy4 to the computer, checked the connection and network, sended some signals to Pybytes through Atom/Pymakr. Then I turned off the Pycom device and connected my DHT11 to extansionboard: ground(brown cable) to GND, VCC to 3VR on the board and finally data to P23.


**Platform**

I used Pybytes cloud plattform and I think its very easy to use, simple with step by step guides. I used free version. Pybytes had good mobile version, in case you want to check your device outside. And firware over the air worked quickly without any errors.

**The code**

The code is attached below:

# https://github.com/JurassicPork/DHT_PyCom
import time
import pycom
from machine import enable_irq, disable_irq,  Pin

class DHTResult:
    'DHT sensor result returned by DHT.read() method'

    ERR_NO_ERROR = 0
    ERR_MISSING_DATA = 1
    ERR_CRC = 2

    error_code = ERR_NO_ERROR
    temperature = -1
    humidity = -1

    def __init__(self, error_code, temperature, humidity):
        self.error_code = error_code
        self.temperature = temperature
        self.humidity = humidity

    def is_valid(self):
        return self.error_code == DHTResult.ERR_NO_ERROR


class DHT:
    'DHT sensor (dht11, dht21,dht22) reader class for Pycom'

    #__pin = Pin('P3', mode=Pin.OPEN_DRAIN)
    __dhttype = 0

    def __init__(self, pin, sensor=0):
        self.__pin = Pin(pin, mode=Pin.OPEN_DRAIN)
        self.__dhttype = sensor
        self.__pin(1)
        time.sleep(1.0)

    def read(self):
        # pull down to low
        self.__send_and_sleep(0, 0.019)
        data = pycom.pulses_get(self.__pin,100)
        self.__pin.init(Pin.OPEN_DRAIN)
        self.__pin(1)
        #print(data)
        bits = []
        for a,b in data:
        	if a ==1 and 18 <= b <= 28:
        		bits.append(0)
        	if a ==1 and 65 <= b <= 75:
        		bits.append(1)
        #print("longueur bits : %d " % len(bits))
        if len(bits) != 40:
            return DHTResult(DHTResult.ERR_MISSING_DATA, 0, 0)
        #print(bits)
        # we have the bits, calculate bytes
        the_bytes = self.__bits_to_bytes(bits)
        # calculate checksum and check
        checksum = self.__calculate_checksum(the_bytes)
        if the_bytes[4] != checksum:
            return DHTResult(DHTResult.ERR_CRC, 0, 0)
        # ok, we have valid data, return it
        [int_rh, dec_rh, int_t, dec_t, csum] = the_bytes
        if self.__dhttype==0:		#dht11
            rh = int_rh 		#dht11 20% ~ 90%
            t = int_t 	#dht11 0..50°C
        else:			#dht21,dht22
            rh = ((int_rh * 256) + dec_rh)/10
            t = (((int_t & 0x7F) * 256) + dec_t)/10
            if (int_t & 0x80) > 0:
                t *= -1
        return DHTResult(DHTResult.ERR_NO_ERROR, t, rh)


    def __send_and_sleep(self, output, mysleep):
        self.__pin(output)
        time.sleep(mysleep)

    def __bits_to_bytes(self, bits):
        the_bytes = []
        byte = 0

        for i in range(0, len(bits)):
            byte = byte << 1
            if (bits[i]):
                byte = byte | 1
            else:
                byte = byte | 0
            if ((i + 1) % 8 == 0):
                the_bytes.append(byte)
                byte = 0
        #print(the_bytes)
        return the_bytes

    def __calculate_checksum(self, the_bytes):
        return the_bytes[0] + the_bytes[1] + the_bytes[2] + the_bytes[3] & 255

# Data is sent to Pybytes. Needs to flashed with Pybyte firmware
import time
from machine import Pin
from dht import DHT # https://github.com/JurassicPork/DHT_PyCom

# Type 0 = dht11
# Type 1 = dht22

th = DHT(Pin('P23', mode=Pin.OPEN_DRAIN), 0)
time.sleep(2)

while True:
    result = th.read()
    while not result.is_valid():
        time.sleep(.5)
        result = th.read()
    print('Temp:', result.temperature)
    print('RH:', result.humidity)
    pybytes.send_signal(1,result.temperature)
    pybytes.send_signal(2,result.humidity)

    time.sleep(5)

DHT and DHTResult classes are responsible for taking the valid information and main class kör några metoder som skickar data till både atom terminal och pybytes.

**Transmitting the data / connectivity**

Data is sent every 7 seconds, and I used Wifi as first choice for network, MQTT protocol.

**Presenting the data**

The data is sent every 7th second to pybytes and displays in the linechart diagram, the example bellow shows last 4 hours.


**Finalizing the design**

I am happy with my discoveries and I find out that it cost for me around 1,8SEK to shower, 2,5SEK for dishwashing and 0,09SEK each time I wash my hands. To use warm water for one minute cost 0,18SEK.

Here is the picture of my device in action