Air Quality Monitor

Introduction

Python-based drivers for

• Sensirion SPS30 particulate matter sensor.
• Sensirion SEN54 environmental sensor node for PM, RH/T, VOC measurements
• Sensirion SEN55 environmental sensor node for PM, RH/T, VOC, NOx measurements
• Sensirion SHT40 .1.8% / max. .3.5% Digital humidity and temperature sensor.
• BOSCH BMP280 absolute barometric pressure sensor

Tested on Raspberry Pi Zero/Zero W2.

Wiring

SPS30 Sensor

                                 Pin 1   Pin 5
                                   |       |
                                   V       V
.------------------------------------------------.
|                                .-----------.   |
|                                | x x x x x |   |
|                                '-----------'   |
|     []          []          []          []     |
'------------------------------------------------'

Pin	Description	UART	I2C
1	Supply voltage 5V	VDD	VDD
2	UART receiving pin/ I2C serial data input/ output	RX	SDA
3	UART transmitting pin/ I2C serial clock input	TX	SCL
4	Interface select (UART: floating (NC) /I2C: GND)	NC	GND
5	Ground	GND	GND

SEN5x Sensor

.---------\                      Pin 6     Pin 1
|          \                       |         |
|           \                      V         V
|--------------------------------------------------.
|                                .-------------.   |
|                                | x x x x x x |   |
|                                '-------------'   |
|     []          []          []          []       |
'--------------------------------------------------'

Pin	Description	I2C
1	Supply voltage 5V	VDD
2	Ground	GND
3	I2C serial data input/ output	SDA
4	I2C serial clock input	SCL
5	Interface select (/I2C: GND)	GND
6	Not connected	-

BMP280 Sensor

Pin	Description	I2C
1	Supply voltage 3.3/5V	VDD
2	Ground	GND
3	I2C serial clock input	SCL
4	I2C serial data input / output	SDA
5	Interface select (I2C: VDD/SPI: GND)	CSB
6	Sensr Addess (0x76: GND / 0x77: VCC)	SDO

I2C Interface

  SPS30 Sensor Pins                           Raspberry Pi Pins 
                                              [default, see below for alternative i2c buses]
.-------.-----.                             .----------.---------.
| Pin 1 | VDD |-----------------------------|    5V    | Pin 2/4 |
| Pin 2 | SDA |-----------------------------| I2C1 SDA |  Pin 3  |
| Pin 3 | SCL |-----------------------------| I2C1 SCL |  Pin 5  |
| Pin 4 | GND |-----.                       |          |         |
| Pin 5 | GND |-----'-----------------------|   GND    | Pin 6/9 |
'-------'-----'                             '----------'---------'

  SEN5x Sensor Pins                           Raspberry Pi Pins
                                              [default, see below for alternative i2c buses]
.-------.-----.                             .----------.---------.
| Pin 1 | VDD |-----------------------------|    5V    | Pin 2/4 |
| Pin 2 | GND |-----------------------------|   GND    | Pin 6/9 |
| Pin 3 | SDA |-----------------------------| I2C1 SDA |  Pin 3  |
| Pin 4 | SCL |-----------------------------| I2C1 SCL |  Pin 5  |
| Pin 5 | SEL |-----------------------------|   GND    | Pin 6/9 |
| Pin 6 | NC  |-------                      |          |         |
'-------'-----'                             '----------'---------'

  BMP280 Sensor Pins                          Raspberry Pi Pins
                                              [default, see below for alternative i2c buses]
.-------.-----.                             .----------.---------.
| Pin 1 | VDD |-----------------------------|    5V    | Pin 2/4 |
| Pin 2 | GND |-----------------------------|   GND    | Pin 6/9 |
| Pin 3 | SCL |-----------------------------| I2C1 SCL |  Pin 5  |
| Pin 4 | SDA |-----------------------------| I2C1 SDA |  Pin 3  |
| Pin 5 | CSB |-----------------------------|   VCC    | Pin 2/4 |
| Pin 6 | SD0 |-----------------------------|   VCC    | Pin 2/4 | 
'-------'-----'                             '----------'---------'

Note: SCL and SDA lines are OPEN DRAIN. They should be connected to external pull-up resistors (E.g. R=10kOhm)

Multiple I2C Interfaces @ RPi

• Raspberry PI Multiple I2C Devices
• Changing the baud rate of additional I2C busses

  sudo nano /boot/config.txt
  
  dtoverlay=i2c-gpio,bus=5,i2c_gpio_delay_us=20,i2c_gpio_sda=5,i2c_gpio_scl=6
  dtoverlay=i2c-gpio,bus=4,i2c_gpio_delay_us=20,i2c_gpio_sda=17,i2c_gpio_scl=22
  dtoverlay=i2c-gpio,bus=3,i2c_gpio_delay_us=20,i2c_gpio_sda=27,i2c_gpio_scl=23

Note: On long i2c lines use i2c_gpio_delay_us=100

Small wiring PCB for Raspberry PI

Install

cd AirQmonitor

git clone https://github.com/pklosko/AirQmonitor

Add your sensor.comminuty ID = SC_SENSOR_ID in AirQmonitor.py

Run after boot

sudo vi /etc/rc.local

su - pi -c '/home/pi/AirQmonitor/AirQmonitor.py'

Example usage

See example.py | exampleSEN.py

Default parameters of SPS30 class

Parameter	Value	Description
bus	1	I2C bus of Raspberry Pi
address	0x69	Default I2C address

Default parameters of SEN5x class

Parameter	Value	Description
bus	1	I2C bus of Raspberry Pi
address	0x69	Default I2C address

Default parameters of SHT40 class

Parameter	Value	Description
bus	1	I2C bus of Raspberry Pi
address	0x44	Default I2C address

Default parameters of BMP280 class

Parameter	Value	Description
bus	1	I2C bus of Raspberry Pi
address	0x77	Default I2C address
oversampling T	1x	temperature oversampling
oversampling p	1x	pressure oversampling
standby time	1s	stand-by time
IIR filter	off	IIR filter
Mode	forced	mode

Output data format

RAW Data - JSON - SPS30

{
  "t": 22.02258335240711,
  "t1": 22.546321267577, 
  "h": 41.55664911879148,
  "p": 100142.342398298,
  "pm1": 1.285,
  "pm2": 5.262,
  "pm4": 9.045,
  "pm10": 10.969,
  "nc0": 1.0,
  "nc1": 1.0,
  "nc2": 4.473,
  "nc4": 5.034,
  "nc10": 5.11,
  "tps": 1.63
}

RAW Data - JSON - SEN5x

{
  "pm1": 1.28,
  "pm2": 5.22,
  "pm4": 9.45,
  "pm10": 10.69,
  "h": 51.0,
  "t": 21.0,
  "voc": 101.9,
  "nox": 3276.7 # SEN54 doesn't have NOx sensor
}

Sensor.commuinty POST API

See api.sensor.community

TMEP.cz

See TMEP.cz Wiki

Dependencies

None

To-Do

None

SPS30 code based on Sensirion SPS30 code by @dvsu