Difference between revisions of "Raspberry Pi Environmental Monitoring"

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Line 1: Line 1:
 
==Purpose==
 
==Purpose==
 
To monitor air temperature, humidity, and air quality.
 
To monitor air temperature, humidity, and air quality.
 +
<br>
 +
<br>
 +
Initially this was put together to run node-red and mysql on a single pi. This worked ok until the database reached ~200MB and the flash drive I was using started to choke. I also noticed the power draw for the pi, monitor, flash drive, and sensors exceeded the supply.
 +
===Work in progress===
 +
*<s>Move database off pi to central home server.</s>
 +
*Move node-red to central server.
 +
*Convert pi to pull from sensors using python instead of node-red.
 +
*Send data to central server using MQTT instead of MySQL
  
−
===Air Quality===
+
==PM Sensor==
−
A friend sent me a Nova PM Sensor. I do not know python yet, but looking over the script that is readily available<ref>https://hackernoon.com/how-to-measure-particulate-matter-with-a-raspberry-pi-75faa470ec35</ref><ref>https://openschoolsolutions.org/measure-particulate-matter-with-a-raspberry-pi/</ref> I should be able to modify this to work for my needs.
+
===Base Script===
 +
A friend sent me a Nova PM Sensor. Found a script that is readily available<ref>https://hackernoon.com/how-to-measure-particulate-matter-with-a-raspberry-pi-75faa470ec35</ref><ref>https://openschoolsolutions.org/measure-particulate-matter-with-a-raspberry-pi/</ref>.
 +
*<b>NOTE</b> : This appears to run in python2. When attempting to run with python3 I received indentation errors. Should be easy to fix, but I am lazy and this is not a critical system.
 
<pre>
 
<pre>
 +
sudo apt install git-core python-serial python-enum python-pip
 
mkdir -p /home/pi/build/air && cd /home/pi/build/air
 
mkdir -p /home/pi/build/air && cd /home/pi/build/air
 
sudo apt install git-core python-serial python-enum mariadb-server python-mysql.connector
 
sudo apt install git-core python-serial python-enum mariadb-server python-mysql.connector
Line 20: Line 31:
 
PM2.5:  0.7 , PM10:  0.7
 
PM2.5:  0.7 , PM10:  0.7
 
</pre>
 
</pre>
 +
*Now remove the print command and instead create variables for pm2.5 and pm10
 +
<pre>
 +
              #print("PM2.5: ", values[0], ", PM10: ", values[1])
 +
      pm25=values[0]
 +
      pm10=values[1]
 +
</pre>
 +
 +
===Send values to MQTT===
 +
*Work in progress.
 +
<ref>https://pypi.org/project/paho-mqtt/#constructor-reinitialise</ref><ref>http://www.steves-internet-guide.com/into-mqtt-python-client/</ref>
 +
*Install python modules for mqtt
 +
<pre>
 +
pip install paho-mqtt
 +
</pre>
 +
*Update the aqi.py script to imnport the module, and configure as seen below.
 +
<b>NOTE : </b> I am using authentication but not encryption in this example.
 +
<pre>
 +
import paho.mqtt.client as mqtt
 +
 +
def mqttpub(pm1,pm2):
 +
    broker_address="xxx.xxx.xxx.xxx"
 +
    username="<username on broker>"
 +
    password="<password on broker>"
 +
    mqttc=mqtt.Client()
 +
    mqttc.username_pw_set(username, password)
 +
    mq = "0"
 +
    while mq == "0":
 +
        try:
 +
            mqttc.connect(broker_address)
 +
        except:
 +
            print("Failed MQTT")
 +
            time.sleep(5)
 +
            mq="0"
 +
        else:
 +
            mq="1"
 +
            mqttc.publish("air/livingroom/pm25",pm1)
 +
            mqttc.publish("air/livingroom/pm10",pm2)
 +
 +
...
 +
              mqttpub(pm25,pm10)
 +
</pre>
 +
 +
===Configure for writing to database (LEGACY)===
 +
*<b>NOTE</b> : This is really not necessary except for historical data purposes, and running on the pi is a bit much.
 
However, I want the history written to a database. Configure mariadb anyway you want, if you have credentials keep them on hand.
 
However, I want the history written to a database. Configure mariadb anyway you want, if you have credentials keep them on hand.
 
<pre>
 
<pre>
Line 42: Line 97:
  
 
</pre>
 
</pre>
−
Now we edit the script to work with mysql<ref>https://www.w3schools.com/python/python_mysql_insert.asp</ref>
+
Now we edit the script to work with mysql<ref>https://www.w3schools.com/python/python_mysql_insert.asp</ref><br>
 +
Please note that of this writing I the script searches the entire database for 0 values and deletes them. I need to go back and update to simply not write 0 values in the first place.
 +
*Edit downloaded script with the following
 +
<pre>
 +
import mysql.connector
 +
 
 +
mydb = mysql.connector.connect(
 +
  host="localhost",
 +
  user="air",
 +
  database="air"
 +
)
 +
...
 +
              mycursor.execute('INSERT INTO aqi (pm25, pm10, date) VALUES (%s, %s, %s)' % (pm25,pm10,'now()'))
 +
              mydb.commit()
 +
              mycursor.execute("delete from aqi where pm10 = 0 and pm25 = 0")
 +
...
 +
              mycursor.execute("delete from aqi where date < (now() - interval 1 year)")
 +
</pre>
 +
===Full Modified Script===
 +
<pre>
 +
#!/usr/bin/python -u
 +
# coding=utf-8
 +
# "DATASHEET": http://cl.ly/ekot
 +
# https://gist.github.com/kadamski/92653913a53baf9dd1a8
 +
from __future__ import print_function
 +
import serial, struct, sys, time, json, subprocess,  mysql.connector
 +
 
 +
time.sleep(120)
 +
 
 +
mydb = mysql.connector.connect(
 +
  host="localhost",
 +
  user="air",
 +
  database="air"
 +
)
 +
 
 +
mycursor = mydb.cursor()
 +
 
 +
DEBUG = 0
 +
CMD_MODE = 2
 +
CMD_QUERY_DATA = 4
 +
CMD_DEVICE_ID = 5
 +
CMD_SLEEP = 6
 +
CMD_FIRMWARE = 7
 +
CMD_WORKING_PERIOD = 8
 +
MODE_ACTIVE = 0
 +
MODE_QUERY = 1
 +
PERIOD_CONTINUOUS = 0
 +
 
 +
ser = serial.Serial()
 +
ser.port = "/dev/ttyUSB0"
 +
ser.baudrate = 9600
 +
 
 +
ser.open()
 +
ser.flushInput()
 +
 
 +
byte, data = 0, ""
 +
 
 +
def dump(d, prefix=''):
 +
    print(prefix + ' '.join(x.encode('hex') for x in d))
 +
 
 +
def construct_command(cmd, data=[]):
 +
    assert len(data) <= 12
 +
    data += [0,]*(12-len(data))
 +
    checksum = (sum(data)+cmd-2)%256
 +
    ret = "\xaa\xb4" + chr(cmd)
 +
    ret += ''.join(chr(x) for x in data)
 +
    ret += "\xff\xff" + chr(checksum) + "\xab"
 +
 
 +
    if DEBUG:
 +
        dump(ret, '> ')
 +
    return ret
 +
 
 +
def process_data(d):
 +
    r = struct.unpack('<HHxxBB', d[2:])
 +
    pm25 = r[0]/10.0
 +
    pm10 = r[1]/10.0
 +
    checksum = sum(ord(v) for v in d[2:8])%256
 +
    return [pm25, pm10]
 +
    #print("PM 2.5: {} μg/m^3  PM 10: {} μg/m^3 CRC={}".format(pm25, pm10, "OK" if (checksum==r[2] and r[3]==0xab) else "NOK"))
 +
 
 +
def process_version(d):
 +
    r = struct.unpack('<BBBHBB', d[3:])
 +
    checksum = sum(ord(v) for v in d[2:8])%256
 +
    print("Y: {}, M: {}, D: {}, ID: {}, CRC={}".format(r[0], r[1], r[2], hex(r[3]), "OK" if (checksum==r[4] and r[5]==0xab) else "NOK"))
 +
 
 +
def read_response():
 +
    byte = 0
 +
    while byte != "\xaa":
 +
        byte = ser.read(size=1)
 +
 
 +
    d = ser.read(size=9)
 +
 
 +
    if DEBUG:
 +
        dump(d, '< ')
 +
    return byte + d
 +
 
 +
def cmd_set_mode(mode=MODE_QUERY):
 +
    ser.write(construct_command(CMD_MODE, [0x1, mode]))
 +
    read_response()
 +
 
 +
def cmd_query_data():
 +
    ser.write(construct_command(CMD_QUERY_DATA))
 +
    d = read_response()
 +
    values = []
 +
    if d[1] == "\xc0":
 +
        values = process_data(d)
 +
    return values
 +
 
 +
def cmd_set_sleep(sleep):
 +
    mode = 0 if sleep else 1
 +
    ser.write(construct_command(CMD_SLEEP, [0x1, mode]))
 +
    read_response()
 +
 
 +
def cmd_set_working_period(period):
 +
    ser.write(construct_command(CMD_WORKING_PERIOD, [0x1, period]))
 +
    read_response()
 +
 
 +
def cmd_firmware_ver():
 +
    ser.write(construct_command(CMD_FIRMWARE))
 +
    d = read_response()
 +
    process_version(d)
 +
 
 +
def cmd_set_id(id):
 +
    id_h = (id>>8) % 256
 +
    id_l = id % 256
 +
    ser.write(construct_command(CMD_DEVICE_ID, [0]*10+[id_l, id_h]))
 +
    read_response()
 +
 
 +
 
 +
if __name__ == "__main__":
 +
    cmd_set_sleep(0)
 +
    cmd_firmware_ver()
 +
    cmd_set_working_period(PERIOD_CONTINUOUS)
 +
    cmd_set_mode(MODE_QUERY);
 +
    while True:
 +
        cmd_set_sleep(0)
 +
        for t in range(15):
 +
            values = cmd_query_data();
 +
            if values is not None and len(values) == 2:
 +
#              print("PM2.5: ", values[0], ", PM10: ", values[1])
 +
      pm25=values[0]
 +
      pm10=values[1]
 +
              mycursor.execute('INSERT INTO aqi (pm25, pm10, date) VALUES (%s, %s, %s)' % (pm25,pm10,'now()'))
 +
              mydb.commit()
 +
              mycursor.execute("delete from aqi where pm10 = 0 and pm25 = 0")
 +
              time.sleep(2)
 +
 
 +
 
 +
        print("Going to sleep for 1 min...")
 +
        cmd_set_sleep(1)
 +
        time.sleep(60)
 +
        mycursor.execute("delete from aqi where date < (now() - interval 1 year)")
 +
</pre>
 +
Configure to run at boot by adding the following to your crontab
 +
<pre>
 +
@reboot /home/pi/build/air/air.py
 +
</pre>
 +
 
 +
==Tempurature / Humidity==
 +
===Using Python to pull from Sensor===
 +
Place holder
 +
===Using Node-Red to pull from Sensor===
 +
NOTE : See https://michaelwiki.geekgalaxy.com/index.php/Raspberry_Pi_Environmental_Monitoring#Graph_Display
 +
<br>
 +
<br>
 +
For this one I decided to use node-red to pull the values directly. It supports raspberry pi GPIO and the DHT-11 sensor I have on hand<ref>https://flows.nodered.org/node/node-red-contrib-dht-sensor</ref>.
 +
*Install the node-red-contrib-dht-sensor packages (I used the web gui)
 +
<pre>
 +
sudo apt install wiringpi
 +
</pre>
 +
*Add inject module with as timestamp. I chose to inject every 5 seconds.
 +
*Add the rpi-dht11 node to the flow, I gave it the following values
 +
**Sensor : DHT11
 +
**Pin numbering : WiringPi (rev.1)
 +
**Pin number : 7
 +
*The dht11 or 22 node will break out to a function and change module.
 +
*This breaks out to a function node that changes C to F <ref>https://groups.google.com/forum/#!topic/node-red/bkmv6kMAFlM</ref>
 +
<pre>
 +
var tempc = msg.payload;
 +
tempf = tempc * 9/5 + 32;
 +
tempf = Math.round(tempf * 10) / 10;
 +
msg.payload = tempf;
 +
return msg;
 +
</pre>
 +
*Now use a change module to change msg.payload to msg.humidity.
 +
*Both the function and change modules connect to MQTT out modules that connect to my MQTT server.
 +
 
 +
==Graph Display==
 +
The same pointed me to node-red for the display. What I really wanted was a nerdy ncurses display, but node-red should suffice until I learn ncurses.
 +
===Install Node-Red===
 +
<ref>https://nodered.org/docs/getting-started/raspberrypi</ref>
 +
When running the install script, make sure the pi settings are applied.
 +
<pre>
 +
bash <(curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)
 +
sudo systemctl enable --now nodered
 +
</pre>
 +
Install the dashboard components<ref>https://flows.nodered.org/node/node-red-dashboard</ref>
 +
===Configure PM 2.5 Flow===
 +
My flow consists of
 +
#An inject node with the timestamp injection using topic <pre>select round(avg(pm25)) from aqi where date < now() - interval 24 hour;</pre>
 +
#A mysql node with the database location and credentials.
 +
#A change node with set to <pre>msg.payload[0].pm25</pre>
 +
#A gauge node set for values between 0.1 and 30<ref>https://en.wikipedia.org/wiki/Air_quality_index</ref>.
 +
<br>
 +
<br>
 +
 
 +
==Configure Pi for Kiosk Mode==
 +
<ref>https://pimylifeup.com/raspberry-pi-kiosk/</ref>Please note that this is not the most secure configuration. In my case the terminal is located in my house, on a segregated wifi network and broadcast domain, and the information contained is air quality metrics so impact of compromise is low.
 +
<pre>
 +
sudo apt-get install lightdm
 +
sudo raspi-config
 +
</pre>
 +
At this point go to boot options, desktop /CLI, then select the desktop autologin. Close the tool and reboot.
 +
*Note : I ran into a login loop where I was unable to auto-login and manually logging in did not work. I found a forum<ref>https://www.raspberrypi.org/forums/viewtopic.php?t=154190</ref> mentioning to install a set of x11 packages as well as openbox. I went ahead with this as I used open box years ago and found it very light weight and useful for such tasks.
 +
<pre>
 +
sudo apt-get install xserver-xorg-core xserver-xorg-input-all \
 +
xserver-xorg-video-fbdev libx11-6 x11-common \
 +
x11-utils x11-xkb-utils x11-xserver-utils xterm lightdm openbox
 +
</pre>
 +
After running the previous the system now logs me into openbox. At this point we want openbox to start chrome in kiosk mode.<ref>https://www.raspberrypi.org/forums/viewtopic.php?t=8298</ref>
 +
<pre>
 +
sudo apt install chromium-browser
 +
mkdir -p ~/.config/openbox && cp /etc/xdg/openbox/* ~/.config/openbox
 +
echo -e "xset s noblank\nxset s off\n\xset -dpms\nunclutter &\nchromium-browser --kiosk http://127.0.0.1:1880/ui" >> ~/.config/openbox/autostart
 +
sudo reboot -h
 +
</pre>
 +
Now you should be booted into openbox with chromium running in kiosk mode, loaded with the node red graphs.

Latest revision as of 09:36, 19 May 2020

Purpose

To monitor air temperature, humidity, and air quality.

Initially this was put together to run node-red and mysql on a single pi. This worked ok until the database reached ~200MB and the flash drive I was using started to choke. I also noticed the power draw for the pi, monitor, flash drive, and sensors exceeded the supply.

Work in progress

  • Move database off pi to central home server.
  • Move node-red to central server.
  • Convert pi to pull from sensors using python instead of node-red.
  • Send data to central server using MQTT instead of MySQL

PM Sensor

Base Script

A friend sent me a Nova PM Sensor. Found a script that is readily available[1][2].

  • NOTE : This appears to run in python2. When attempting to run with python3 I received indentation errors. Should be easy to fix, but I am lazy and this is not a critical system.
sudo apt install git-core python-serial python-enum python-pip
mkdir -p /home/pi/build/air && cd /home/pi/build/air
sudo apt install git-core python-serial python-enum mariadb-server python-mysql.connector
wget -O aqi.py https://raw.githubusercontent.com/zefanja/aqi/master/python/aqi.py
echo [] > aqi.json
sed -i 's|/var/www/html/aqi.json|/home/pi/build/air/aqi.json|' aqi.py

At this point we can run the script, see output on the screen, and see the history written to the json file. 

./aqi.py 
Y: 18, M: 1, D: 18, ID: 0xbc2d, CRC=OK
PM2.5:  0.0 , PM10:  0.0
PM2.5:  0.7 , PM10:  0.7
PM2.5:  0.6 , PM10:  0.6
PM2.5:  0.7 , PM10:  0.7
  • Now remove the print command and instead create variables for pm2.5 and pm10
              #print("PM2.5: ", values[0], ", PM10: ", values[1])
	      pm25=values[0]
	      pm10=values[1]

Send values to MQTT

  • Work in progress.

[3][4]

  • Install python modules for mqtt
pip install paho-mqtt
  • Update the aqi.py script to imnport the module, and configure as seen below.

NOTE : I am using authentication but not encryption in this example. 

import paho.mqtt.client as mqtt

def mqttpub(pm1,pm2):
    broker_address="xxx.xxx.xxx.xxx"
    username="<username on broker>"
    password="<password on broker>"
    mqttc=mqtt.Client()
    mqttc.username_pw_set(username, password)
    mq = "0"
    while mq == "0":
        try:
            mqttc.connect(broker_address)
        except:
            print("Failed MQTT")
            time.sleep(5)
            mq="0"
        else:
            mq="1"
            mqttc.publish("air/livingroom/pm25",pm1)
            mqttc.publish("air/livingroom/pm10",pm2)

...
              mqttpub(pm25,pm10)

Configure for writing to database (LEGACY)

  • NOTE : This is really not necessary except for historical data purposes, and running on the pi is a bit much.

However, I want the history written to a database. Configure mariadb anyway you want, if you have credentials keep them on hand. 

create database air;
create user air;
grant all on air.* to 'air';
use air;
create table aqi (pm25 FLOAT, pm10 FLOAT, date DATETIME);
select * from aqi;
Empty set (0.00 sec)

insert into aqi values (2.1, 2.3, now());
Query OK, 1 row affected (0.02 sec)

select * from aqi;
+------+------+---------------------+
| pm25 | pm10 | date                |
+------+------+---------------------+
|  2.1 |  2.3 | 2019-12-20 13:32:18 |
+------+------+---------------------+
1 row in set (0.00 sec)

Now we edit the script to work with mysql[5]
Please note that of this writing I the script searches the entire database for 0 values and deletes them. I need to go back and update to simply not write 0 values in the first place.

  • Edit downloaded script with the following
import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="air",
  database="air"
)
...
              mycursor.execute('INSERT INTO aqi (pm25, pm10, date) VALUES (%s, %s, %s)' % (pm25,pm10,'now()'))
              mydb.commit()
              mycursor.execute("delete from aqi where pm10 = 0 and pm25 = 0")
...
              mycursor.execute("delete from aqi where date < (now() - interval 1 year)")

Full Modified Script

#!/usr/bin/python -u
# coding=utf-8
# "DATASHEET": http://cl.ly/ekot
# https://gist.github.com/kadamski/92653913a53baf9dd1a8
from __future__ import print_function
import serial, struct, sys, time, json, subprocess,  mysql.connector

time.sleep(120)

mydb = mysql.connector.connect(
  host="localhost",
  user="air",
  database="air"
)

mycursor = mydb.cursor()

DEBUG = 0
CMD_MODE = 2
CMD_QUERY_DATA = 4
CMD_DEVICE_ID = 5
CMD_SLEEP = 6
CMD_FIRMWARE = 7
CMD_WORKING_PERIOD = 8
MODE_ACTIVE = 0
MODE_QUERY = 1
PERIOD_CONTINUOUS = 0

ser = serial.Serial()
ser.port = "/dev/ttyUSB0"
ser.baudrate = 9600

ser.open()
ser.flushInput()

byte, data = 0, ""

def dump(d, prefix=''):
    print(prefix + ' '.join(x.encode('hex') for x in d))

def construct_command(cmd, data=[]):
    assert len(data) <= 12
    data += [0,]*(12-len(data))
    checksum = (sum(data)+cmd-2)%256
    ret = "\xaa\xb4" + chr(cmd)
    ret += ''.join(chr(x) for x in data)
    ret += "\xff\xff" + chr(checksum) + "\xab"

    if DEBUG:
        dump(ret, '> ')
    return ret

def process_data(d):
    r = struct.unpack('<HHxxBB', d[2:])
    pm25 = r[0]/10.0
    pm10 = r[1]/10.0
    checksum = sum(ord(v) for v in d[2:8])%256
    return [pm25, pm10]
    #print("PM 2.5: {} μg/m^3  PM 10: {} μg/m^3 CRC={}".format(pm25, pm10, "OK" if (checksum==r[2] and r[3]==0xab) else "NOK"))

def process_version(d):
    r = struct.unpack('<BBBHBB', d[3:])
    checksum = sum(ord(v) for v in d[2:8])%256
    print("Y: {}, M: {}, D: {}, ID: {}, CRC={}".format(r[0], r[1], r[2], hex(r[3]), "OK" if (checksum==r[4] and r[5]==0xab) else "NOK"))

def read_response():
    byte = 0
    while byte != "\xaa":
        byte = ser.read(size=1)

    d = ser.read(size=9)

    if DEBUG:
        dump(d, '< ')
    return byte + d

def cmd_set_mode(mode=MODE_QUERY):
    ser.write(construct_command(CMD_MODE, [0x1, mode]))
    read_response()

def cmd_query_data():
    ser.write(construct_command(CMD_QUERY_DATA))
    d = read_response()
    values = []
    if d[1] == "\xc0":
        values = process_data(d)
    return values

def cmd_set_sleep(sleep):
    mode = 0 if sleep else 1
    ser.write(construct_command(CMD_SLEEP, [0x1, mode]))
    read_response()

def cmd_set_working_period(period):
    ser.write(construct_command(CMD_WORKING_PERIOD, [0x1, period]))
    read_response()

def cmd_firmware_ver():
    ser.write(construct_command(CMD_FIRMWARE))
    d = read_response()
    process_version(d)

def cmd_set_id(id):
    id_h = (id>>8) % 256
    id_l = id % 256
    ser.write(construct_command(CMD_DEVICE_ID, [0]*10+[id_l, id_h]))
    read_response()


if __name__ == "__main__":
    cmd_set_sleep(0)
    cmd_firmware_ver()
    cmd_set_working_period(PERIOD_CONTINUOUS)
    cmd_set_mode(MODE_QUERY);
    while True:
        cmd_set_sleep(0)
        for t in range(15):
            values = cmd_query_data();
            if values is not None and len(values) == 2:
#              print("PM2.5: ", values[0], ", PM10: ", values[1])
	      pm25=values[0]
	      pm10=values[1]
              mycursor.execute('INSERT INTO aqi (pm25, pm10, date) VALUES (%s, %s, %s)' % (pm25,pm10,'now()'))
              mydb.commit()
              mycursor.execute("delete from aqi where pm10 = 0 and pm25 = 0")
              time.sleep(2)


        print("Going to sleep for 1 min...")
        cmd_set_sleep(1)
        time.sleep(60)
        mycursor.execute("delete from aqi where date < (now() - interval 1 year)")

Configure to run at boot by adding the following to your crontab 

@reboot /home/pi/build/air/air.py

Tempurature / Humidity

Using Python to pull from Sensor

Place holder

Using Node-Red to pull from Sensor

NOTE : See https://michaelwiki.geekgalaxy.com/index.php/Raspberry_Pi_Environmental_Monitoring#Graph_Display

For this one I decided to use node-red to pull the values directly. It supports raspberry pi GPIO and the DHT-11 sensor I have on hand[6].

  • Install the node-red-contrib-dht-sensor packages (I used the web gui)
sudo apt install wiringpi
  • Add inject module with as timestamp. I chose to inject every 5 seconds.
  • Add the rpi-dht11 node to the flow, I gave it the following values
    • Sensor : DHT11
    • Pin numbering : WiringPi (rev.1)
    • Pin number : 7
  • The dht11 or 22 node will break out to a function and change module.
  • This breaks out to a function node that changes C to F [7]
var tempc = msg.payload;
tempf = tempc * 9/5 + 32;
tempf = Math.round(tempf * 10) / 10;
msg.payload = tempf;
return msg;
  • Now use a change module to change msg.payload to msg.humidity.
  • Both the function and change modules connect to MQTT out modules that connect to my MQTT server.

Graph Display

The same pointed me to node-red for the display. What I really wanted was a nerdy ncurses display, but node-red should suffice until I learn ncurses.

Install Node-Red

[8] When running the install script, make sure the pi settings are applied. 

bash <(curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)
sudo systemctl enable --now nodered

Install the dashboard components[9]

Configure PM 2.5 Flow

My flow consists of

  1. An inject node with the timestamp injection using topic 
    select round(avg(pm25)) from aqi where date < now() - interval 24 hour;
  2. A mysql node with the database location and credentials.
  3. A change node with set to 
    msg.payload[0].pm25
  4. A gauge node set for values between 0.1 and 30[10].



Configure Pi for Kiosk Mode

[11]Please note that this is not the most secure configuration. In my case the terminal is located in my house, on a segregated wifi network and broadcast domain, and the information contained is air quality metrics so impact of compromise is low. 

sudo apt-get install lightdm
sudo raspi-config

At this point go to boot options, desktop /CLI, then select the desktop autologin. Close the tool and reboot.

  • Note : I ran into a login loop where I was unable to auto-login and manually logging in did not work. I found a forum[12] mentioning to install a set of x11 packages as well as openbox. I went ahead with this as I used open box years ago and found it very light weight and useful for such tasks.
sudo apt-get install xserver-xorg-core xserver-xorg-input-all \
xserver-xorg-video-fbdev libx11-6 x11-common \
x11-utils x11-xkb-utils x11-xserver-utils xterm lightdm openbox

After running the previous the system now logs me into openbox. At this point we want openbox to start chrome in kiosk mode.[13] 

sudo apt install chromium-browser
mkdir -p ~/.config/openbox && cp /etc/xdg/openbox/* ~/.config/openbox
echo -e "xset s noblank\nxset s off\n\xset -dpms\nunclutter &\nchromium-browser --kiosk http://127.0.0.1:1880/ui" >> ~/.config/openbox/autostart
sudo reboot -h

Now you should be booted into openbox with chromium running in kiosk mode, loaded with the node red graphs.

  1. ↑ https://hackernoon.com/how-to-measure-particulate-matter-with-a-raspberry-pi-75faa470ec35
  2. ↑ https://openschoolsolutions.org/measure-particulate-matter-with-a-raspberry-pi/
  3. ↑ https://pypi.org/project/paho-mqtt/#constructor-reinitialise
  4. ↑ http://www.steves-internet-guide.com/into-mqtt-python-client/
  5. ↑ https://www.w3schools.com/python/python_mysql_insert.asp
  6. ↑ https://flows.nodered.org/node/node-red-contrib-dht-sensor
  7. ↑ https://groups.google.com/forum/#!topic/node-red/bkmv6kMAFlM
  8. ↑ https://nodered.org/docs/getting-started/raspberrypi
  9. ↑ https://flows.nodered.org/node/node-red-dashboard
  10. ↑ https://en.wikipedia.org/wiki/Air_quality_index
  11. ↑ https://pimylifeup.com/raspberry-pi-kiosk/
  12. ↑ https://www.raspberrypi.org/forums/viewtopic.php?t=154190
  13. ↑ https://www.raspberrypi.org/forums/viewtopic.php?t=8298
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