mh-z19 0.1.1

mh_z19 CO2 concentration sensor library for Raspberry Pi

mh-z19

Read CO2 concentration from mh-z19 sensor& send to MONITOR server

install

download from release

or

git clone https://github.com/UedaTakeyuki/mh-z19.git

setup

Setup environment & install prerequired modules by

./setup.sh 

cabling

Connect RPi & mh-z19 as:

• 5V on RPi and Vin on mh-z19
• GND(0v) on RPi and GND on mh-z19
• TxD and RxD are connect to cross between RPi and mh-z18

Followings are example of cabling, but you can free to use other 5v and 0v Pin on the RPi.

pi@raspberrypi:~/mh-z19 $ gpio readall
 +-----+-----+---------+------+---+---Pi B+--+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 |     |     |    3.3v |      |   |  1 || 2  |   |      | 5v      |     |     |
 |   2 |   8 |   SDA.1 |   IN | 1 |  3 || 4  |   |      | 5v      |     |     |  <---- with Vin on mh-z19
 |   3 |   9 |   SCL.1 |   IN | 1 |  5 || 6  |   |      | 0v      |     |     |  <---- with Gnd on mh-z19
 |   4 |   7 | GPIO. 7 |   IN | 1 |  7 || 8  | 1 | ALT0 | TxD     | 15  | 14  |  <---- with RxD on mh-z19
 |     |     |      0v |      |   |  9 || 10 | 1 | ALT0 | RxD     | 16  | 15  |  <---- with TxD on mh-z19
 |  17 |   0 | GPIO. 0 |   IN | 0 | 11 || 12 | 0 | IN   | GPIO. 1 | 1   | 18  |
 |  27 |   2 | GPIO. 2 |   IN | 0 | 13 || 14 |   |      | 0v      |     |     |
 |  22 |   3 | GPIO. 3 |   IN | 0 | 15 || 16 | 0 | IN   | GPIO. 4 | 4   | 23  |
 |     |     |    3.3v |      |   | 17 || 18 | 0 | IN   | GPIO. 5 | 5   | 24  |
 |  10 |  12 |    MOSI |   IN | 0 | 19 || 20 |   |      | 0v      |     |     |
 |   9 |  13 |    MISO |   IN | 0 | 21 || 22 | 0 | IN   | GPIO. 6 | 6   | 25  |
 |  11 |  14 |    SCLK |   IN | 0 | 23 || 24 | 1 | IN   | CE0     | 10  | 8   |
 |     |     |      0v |      |   | 25 || 26 | 1 | IN   | CE1     | 11  | 7   |
 |   0 |  30 |   SDA.0 |   IN | 1 | 27 || 28 | 1 | IN   | SCL.0   | 31  | 1   |
 |   5 |  21 | GPIO.21 |   IN | 1 | 29 || 30 |   |      | 0v      |     |     |
 |   6 |  22 | GPIO.22 |   IN | 1 | 31 || 32 | 0 | IN   | GPIO.26 | 26  | 12  |
 |  13 |  23 | GPIO.23 |   IN | 0 | 33 || 34 |   |      | 0v      |     |     |
 |  19 |  24 | GPIO.24 |   IN | 0 | 35 || 36 | 0 | IN   | GPIO.27 | 27  | 16  |
 |  26 |  25 | GPIO.25 |   IN | 0 | 37 || 38 | 0 | IN   | GPIO.28 | 28  | 20  |
 |     |     |      0v |      |   | 39 || 40 | 0 | IN   | GPIO.29 | 29  | 21  |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+---Pi B+--+---+------+---------+-----+-----+

set view_id

Make sure your view_id on your account of the MONITOR, let's say it was ABCDEF, set it by setid.sh as

./setid.sh ABCDEF

test for getting CO2 Sensor value

sudo python mh_z19.py

In case succeeded, espected response is as follows:

pi@raspberrypi:~/mh-z19 $ sudo python mh_z19.py
{'co2': 420}

In case everything succeeded, expected response is consist of the log of taking photo, sending it, and {"ok":true} as follows:

or, return None in case

• Cabling between RPi & sensor is not correct.
• Sensor is no work.
• setup mentioned before is not finished, or not rebooted after setup.

test for sending CO2 Sensor value

sudo python read.py

In case something wrong, response finished with {"ok":false,"reason":"XXX"}. For Example:

{"ok":false,"reason":"ViewID not valid"}

In case, you should make sure if correct view_is was set by setid.sh command.

setting for automatically run view.sh at 5 minute interval

You can do it both by setting crontab if you're used to do so, or you can use autostart.sh command as follows:

# set autostart on
./autostart.sh --on

# set autostart off
./autostart.sh --off

Tecknically speaking, autostart.sh doesn't use crontab, instead, prepare service for interval running of view.sh named view.service . You can confirm current status of view.service with following command:

sudo systemctl status view.service

In case view.service is running, you can see the log of current status and taking & sending photo as follows:

pi@raspberrypi:~/view-v_1.1.1 $ sudo systemctl status view.service 
● view.service - Take photos & Post to the monitor
   Loaded: loaded (/home/pi/view-v_1.1.1/view.service; enabled; vendor preset: e
   Active: active (running) since Thu 2018-08-23 19:07:24 JST; 4min 40s ago
 Main PID: 777 (loop.sh)
   CGroup: /system.slice/view.service
           ├─777 /bin/bash /home/pi/view-v_1.1.1/loop.sh
           └─820 sleep 5m

Aug 23 19:07:26 raspberrypi loop.sh[777]: --- Capturing frame...
Aug 23 19:07:26 raspberrypi loop.sh[777]: Skipping 20 frames...
Aug 23 19:07:28 raspberrypi loop.sh[777]: Capturing 1 frames...
Aug 23 19:07:28 raspberrypi loop.sh[777]: Captured 21 frames in 1.73 seconds. (1
Aug 23 19:07:28 raspberrypi loop.sh[777]: --- Processing captured image...
Aug 23 19:07:29 raspberrypi loop.sh[777]: Writing JPEG image to '/tmp/2018082319
Aug 23 19:07:29 raspberrypi loop.sh[777]:   % Total    % Received % Xferd  Avera
Aug 23 19:07:29 raspberrypi loop.sh[777]:                                  Dload
Aug 23 19:07:53 raspberrypi loop.sh[777]: [2.0K blob data]
Aug 23 19:07:53 raspberrypi loop.sh[777]:      0
lines 1-18/18 (END)

In case afte service set as off, you can see followings:

pi@raspberrypi:~/view-v_1.1.1 $ sudo systemctl status view.service 
Unit view.service could not be found.

Q&A

Any questions, suggestions, reports are welcome! Please make issue without hesitation!