Website (D3.js) for Raspberry Pi temperature and humidity (DHT11)

Small project on a raspberry pi

• to collect temperature and humidity data via DHT 11 sensor
• run webserver (ngnix) on raspberry pi
• publish a local website to show data as graph (d3.js)

Setup hardware

# DHT-11
._________________.
|.................|__ 4 -> GND (-) -> Ground
|.................|__ 3 -> Into nowhere 
|.................|__ 2 -> Resistor (4,7kOhm) -> GPIO 4 {Resistor End to 3V3 Power}
|_________________|__ 1 -> 3V3 Power (+) -> Power

Install AdafruitDHT Library

Adafruit Python DHT Sensor Library

Do some preperation

sudo apt-get update
sudo apt-get install build-essential python-dev

Clone the GitHub Repository

git clone https://github.com/adafruit/Adafruit_Python_DHT.git

Install the script from repository

cd Adafruit_Python_DHT/

sudo python setup.py install

Got an error?

Traceback (most recent call last):
  File "setup.py", line 1, in <module>
    from setuptools import setup, find_packages, Extension
ImportError: No module named setuptools

Install pythonX-setuptools

# To install setuptools on Debian:
sudo apt-get install python3-setuptools

# For an older version of Python (Python 2.x):
sudo apt-get install python-setuptools

First test with AdafruitDHT

Go to example folder

cd examples
sudo ./AdafruitDHT.py 11 4

The first parameter (11) indicates which sensor was used (22 for the DHT22) and the second, to which GPIO it is connected (not the pin number, but the GPIO number).

# This produces an output like the following:
emp=24.0*  Humidity=41.0%

Attention: The sensors are only ready every two seconds. Be careful not to start a query every second.

Add AdafruitDHT Library to projects

To integrate the Raspberry Pi humidity library into other (Python) projects, you only need the following:

import Adafruit_DHT

# ...

sensor = Adafruit_DHT.DHT11
pin = 4
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)

#...

Use it

You can use the script Write data into csv-file

Crontab

Want to run it on crontab? (e.g. every hour, day, ...)

💡 Executive file must be (sudo chmod +x name-of-csv-file.xyz)

Add this to crontab -e

# Every 5min
5 * * * * python /home/pi/PATH/TO/SCRPT

Need sudo?

Use root's crontab

Run the following command:

sudo crontab -e

Syntax

#### Syntax
The syntax is:
1 2 3 4 5 /path/to/command arg1 arg2
OR
1 2 3 4 5 /root/backup.sh

Where,

1: Minute (0-59)
2: Hours (0-23)
3: Day (0-31)
4: Month (0-12 [12 == December])
5: Day of the week(0-7 [7 or 0 == sunday])
/path/to/command – Script or command name to schedule

Easy to remember format:
* * * * * command to be executed
- - - - -
| | | | |
| | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
| | | ------- Month (1 - 12)
| | --------- Day of month (1 - 31)
| ----------- Hour (0 - 23)
------------- Minute (0 - 59)

Install webserver on raspberry pi

How to setup a website on the raspberry. Only with open source software

💡 Nginx is running on Port 80, make sure nothing else is running there! (Apache 2, PiHole,..)

Update

# Make sure everything is up to date
apt-get update
apt-get upgrade

Setup

1. Install Nginx

sudo apt install nginx

2. Check if it works

# On Raspberry PI
curl localhost

# On any other maschine
curl <IP-of-Raspberry-Pi>

Automatically start nginx on boot

We just issue the following command to make sure the nginx webserver is always started on bootup:

sudo update-rc.d -f nginx defaults;

Edit HTML-File

Go to /var/www/html/ and edit everything you want. You have to use sudo!

Use d3.js

💡 CSV-file must be in the same folder! CSV-file must be (sudo chmod +x name-of-csv-file.csv)

You can find the HTML-file here And the JS-files here (index.js) and here (grid.js)

Example CSV

Date,Disk_usage,CPU,Memory,CPU_TEMP,DHT11_Temperature,DHT11_Humidity
2021-12-02 20:05:05.336617,14.7,0.0,0,23.8,15.0,60.0
2021-12-02 20:08:18.767502,14.7,0.0,0,23.5,17.0,61.0
2021-12-02 20:09:30.924323,14.7,5.1,0,23.4,20.0,62.0