Work with People Monitoring in Python with Raspberry Pi

Tutorial

Trying to connect my DS18B20 temperature sensor to my smart greenhouse , I found that the Internet does not have full instructions for connecting this sensor using the Python programming language. I use it as I work with the Raspberry Pi platform. I decided to fix this problem. It turns out to work with TCP is not so difficult, but you need to understand what we are doing and why. A two-hour dance with a tambourine obviously pissed me off. So here, in addition to the program part itself, I want to tell the whole algorithm from beginning to end. I think that other sensors work similarly, so a large article will be the same for everyone. I hope that if you want to connect your sensor, you will not need a tambourine already :) And so, let's get started, I ask you under Habrokat.

Shamanism with a sensor

For we need to connect the sensor itself. I will work with the DS18B20 temperature sensor. There are lots of articles on this topic, we will not duplicate them. About the connection you can read here . Then we need to get data from the sensor. We will do the same as stated in the article above. There is a great example in Python, of which I am a fan.

import os
tfile=open("/sys/bus/w1/devices/28-000000d7970b/w1_slave")
ttext=tfile.read()
tfile.close()
temp=ttext.split("\n")[1].split(" ")[9]
temperature=float(temp[2:])/1000print temperature

Do not forget to replace the data on your sensor.

As we can see, the temperature takes the variable temperature (who would have thought), and that we will need further.

We conjure with monitoring

Well, first you need to register narodmon.ru , those who have not done it yet. The service API offers us to transfer data using the TCP protocol. So do. We are asked to transmit the text in the following format:

#MAC[#NAME][#LAT][#LNG][#ELE]\n#mac1#value1[#time1][#name1]\n
...
#macN#valueN[#timeN][#nameN]\n
##

But in fact, we need to pass only three parameters: the device MAC, the sensor name and its value. The rest is not necessary, and we do not really need it.

In the first line, we need to pass the hash, MAC, and the newline character \ n.
In the second and subsequent lines, we again transmit the grid, sensor name, grid again and sensor readings. We end this with a newline character \ n.
In the last line, you must pass two grids to complete the package.

As a result, the format remains as follows:

#MAC\n#mac1#value1\n#macN#valueN\n##

We write the program in Python

We will write the program in Python 2. The algorithm will be like this. Receive data from the sensor and write to the variable temperature. Then we form the package and send it to the server of the National Monitoring. We will run the script every 10 minutes (the minimum allowed interval for sending readings is 5 minutes) via cron.

Sending occurs as follows (example shown on the monitoring site):

Send script code

#!/usr/bin/env python2# -*- coding: utf-8 -*-# by Roman Vishnevsky aka.x0x01 @ gmail.comimport socket
# MAC адрес устройства. Заменить на свой!
DEVICE_MAC = '0123456789012'# идентификатор устройства, для простоты добавляется 01 (02) к mac устройства
SENSOR_ID_1 = DEVICE_MAC + '01'
SENSOR_ID_2 = DEVICE_MAC + '02'# значения датчиков, тип float/integer
sensor_value_1 = 20
sensor_value_2 = -20.25# создание сокета
sock = socket.socket()
# обработчик исключенийtry:
    # подключаемся к сокету
    sock.connect(('narodmon.ru', 8283))
    # пишем в сокет еденичное значение датчика
    sock.send("#{}\n#{}#{}\n##".format(DEVICE_MAC, SENSOR_ID_1, sensor_value_1))
    # пишем в сокет множественные значение датчиков# sock.send("#{}\n#{}#{}\n#{}#{}\n##".format(DEVICE_MAC, SENSOR_ID_1, sensor_value_1, SENSOR_ID_2, sensor_value_2))# читаем ответ
    data = sock.recv(1024)
    sock.close()
    print data
except socket.error, e:
    print('ERROR! Exception {}'.format(e))

We connect to the server narodmon.ru:8283

As a result, we get this script:

Ready script code

#!/usr/bin/env python2# -*- coding: utf-8 -*-import socket
import os
import fnmatch
# MAC адрес устройства. Заменить на свой!
DEVICE_MAC = 'FF:FF:FF:FF:FF:FF'#Имена датчиков
SENSOR_ID_1 = 'T1'
SENSOR_ID_2 = 'T2'#Читаем значения датчиков
temperature = []
IDs = []
for filename in os.listdir("/sys/bus/w1/devices"):
  if fnmatch.fnmatch(filename, '28-031652ddbdff'):
    with open("/sys/bus/w1/devices/" + filename + "/w1_slave") as fileobj:
        lines = fileobj.readlines()
    if lines[0].find("YES"):
        pok = lines[1].find('=')
        temperature.append(float(lines[1][pok+1:pok+7])/1000)
        IDs.append(filename)
    else:
          logger.error("Error reading sensor with ID: %s" % (filename))
temperature2 = []
for filename in os.listdir("/sys/bus/w1/devices"):
  if fnmatch.fnmatch(filename, '28-011563e8d2ff'):
    with open("/sys/bus/w1/devices/" + filename + "/w1_slave") as fileobj:
        lines = fileobj.readlines()
    if lines[0].find("YES"):
        pok = lines[1].find('=')
        temperature2.append(float(lines[1][pok+1:pok+7])/1000)
        IDs.append(filename)
    else:
          logger.error("Error reading sensor with ID: %s" % (filename))
sock = socket.socket()
#Подключаемсяtry:
    sock.connect(('narodmon.ru', 8283))
#Создаём маску, заносим в неё данные и передаём их
    sock.send("#{}\n#{}#{}\n#{}#{}\n##".format(DEVICE_MAC, SENSOR_ID_1, str(temperature)[1:-1], SENSOR_ID_2, str(temperature2)[1:-1]))
#Получаем ответ
    data=sock.recv(1024)
    sock.close()
    print data
except socket.error, e:
    print('ERROR! Exception {}'.format(e))
print str(temperature)[1:-1]
print str(temperature2)[1:-1]

This is how sending data from two sensors looks like. If you give the sensor a name starting with T, the server itself will determine that it is a temperature sensor.

Now we need to add a sensor to cron. We type: crontab -eand add there this line:

*/10 * * * * sudo python /home/pi/narod.py

We are waiting for the script to start.

Now we go here narodmon.ru/ip and see if the data has been transmitted. If everything is in order, then click on the “Add device” button on the main page in the menu and specify the MAC. Now we can customize everything to taste (name, type, location, etc.). The sensor can be made public one day after the start of the transfer of evidence.

That's all. I wish you good luck in connecting sensors. Do it more often, because it is so convenient from home to see the temperature in advance at the place where you are going.

See you soon :)

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