I installed at my home the heat pump. This kind of device consumes some electrical energy to transfer heat to my home. I am really curious how much electrical energy needs this device daily. So I decided to monitor main electricity meter of my home. I bought raspberry pi zero W, picamera version 1.3. I am capturing frames of electricity meter digit display by CRON in defined period. Every image is digitally preprocessed. It is recognised position of the display in the frame and seven digits as you can see on images bellow. The really nice article about digits recognition with opencv and python is here. The article inspired me a lot and I only modified the described code to fit to my project. After is image digits recognized to number, the number is stored to mongodb with timestamp. The rpi Zero W is used only for processing images and calling some mongoDB client to store data to other CentOs server. The Centos Server is used for running mongoDB and web server, where web presentation of energy results is hosted.
I started use optical electricity meter reader for reading energy values from electricity meter. I am using serial communication between reader and electricity meter according to norm ČSN EN IEC 62056-8-4. Thats mean that I am not using CAMERA picture parsing anymore. But I like Camera solution because it is cheaper and interesting. So I am keeping the information about that also here.
Main script which I am using now is called
usb.py
This script is based on three parts. Firstly Serial communication between reader and meter. I started 7 bit, even parity, 300 baud serial communication. The serial request is sent and response is parsed and stored in the memory. Secondly Background time period scheduler is used because IR receiver/transmitter communication takes some time to have data available. Thirdly Flask library for creation HTTP REST service. REST service can be read with any other application for results visualisation.
curl http://192.168.0.100:5000/electricity_meter/api/v1.0/energy
{"energy":{"highTarif":"0004200.177","lowTarif":"0021209.409","suma":"0025409.587"}}
I am using python 3.9.1.
Guide is from
#Download
wget https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tgz
#Extract and install
sudo tar zxf Python-3.9.1.tgz
cd Python-3.9.1
sudo ./configure --enable-optimizations
sudo make -j 4
sudo make altinstall
#Make as default
echo "alias python=/usr/local/bin/python3.9" >> ~/.bashrc
source ~/.bashrc
Install and upgrade pip
python -m pip install --upgrade pip
Install virtual env
pip install virtualenv
Create virtual env
virtualenv venv
Activate virtual env
source venv/bin/activate
Install necessary libraries
pip install pyserial
pip install flask
pip install apscheduler
Create system service
sudo nano optical_sensor.service
[Unit]
Description=Optical Sensor Service
[Service]
User=pi
WorkingDirectory=/home/pi/power_meter
ExecStart=/home/pi/power_meter/usb.py
[Install]
WantedBy=multi-user.target
Enable Service
sudo systemctl daemon-reload
sudo systemctl enable optical_sensor.service
sudo systemctl start optical_sensor.service
Every 30 minutes is readed elecrical energy values from api and are saved to elastic search.
run.sh
#!/bin/bash
data=$(curl -X GET http://192.168.0.100:5000/electricity_meter/api/v1.0/energy)
curl -XPOST "http://192.168.0.80:9200/electrical_energy/_doc?pretty" -H 'Content-Type: application/json' -d "$data"
CRON
# every 30 minutes
*/30 * * * * /usr/bin/sh /home/ubuntu/add_energy_to_elastic/run.sh
For installation opencv I followed these instructions.
#Enable my Pi Zero repository:
echo 'deb [trusted=yes] http://dl.bintray.com/yoursunny/PiZero stretch-backports main' |\
sudo tee /etc/apt/sources.list.d/bintray-yoursunny-PiZero.list
#Update package lists:
sudo apt update
#Install OpenCV package:
sudo apt install python3-opencv
#Depending on the speed of your Internet connection, this may take between 15 and 30 minutes.
#Verify the installation:
python3 -c 'import cv2; print(cv2.__version__)'
#It will take around 30 seconds, and then you should see:
#3.2.0After that I installed some missing python libraries
sudo apt-get install libatlas-base-dev
sudo pip3 install scipy
sudo pip3 install imutils
I use my Centos server for storing data and web presentation of results. I followed instructions here to install.
Create repo file for MongoDB last stable version
sudo vi /etc/yum.repos.d/mongodb-org.repo
Content of file should be similar to this
[mongodb-org-4.0]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.0/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-4.0.asc
Install command
sudo yum install mongodb-org
Enable and start mongodb service
sudo systemctl enable mongod
sudo systemctl start mongod
I wanted to access mongodb also with different places than localhost. I open mongodb port to public zone by firewall
sudo firewall-cmd --permanent --zone=public --add-port=27017/tcp
Also don't forget changed Net part in file /etc/mongod.conf to bindIpAll
sudo vi /etc/mongod.conf
net:
port: 27017
bindIpAll: true # Enter 0.0.0.0,:: to bind to all IPv4 and IPv6 addresses or, alternatively, use the net.bindIpAll setting.
For add new user to mongodb Follow these instructions
Install python library pymongo for CRUD operations
sudo pip3 install pymongo
Nice tutorial is here
My Mongo client for storing necessary data looks like this
try:
client = MongoClient('mongodb://x.xxx.xxx.xx:27017',
username = credentials[0][0],
password = credentials[0][1],
authSource = 'home',
authMechanism = 'SCRAM-SHA-1')
timestamp = time.time()
energy = {
'T1' : t1,
'T2' : t2,
'timestamp' : timestamp
}
db = client.home
result = db.energy.insert_one(energy)
finally:
client.close()
I want to store current values to mongodb every 15 minutes
crontab -e
This command open the file with scheduler Write this similar schedule to the file with right path
*/15 * * * * python3 ~/power_meter/digits_recognition/capture_digits.py
For cron trouble shooting use
grep CRON /var/log/syslog
You should have installed postfix for more info about issue
sudo aptitude install postfix
Look here after postfix is correctly set up
sudo tail -f /var/mail/<user>
python3 capture_digits.py
Results should be look similar this
# segments recognition
[1, 1, 1, 1, 0, 1, 1]
[1, 1, 1, 1, 1, 1, 1]
[1, 0, 1, 1, 1, 0, 1]
[1, 1, 1, 0, 1, 1, 1]
[1, 1, 1, 0, 1, 1, 1]
[1, 1, 1, 0, 1, 1, 1]
[1, 1, 1, 0, 1, 1, 0]
# digits recognition
[9, 8, 2, 0, 0, 0, 0]