dvsu / sps30

Python-based driver for Sensirion SPS30 particulate matter sensor. Tested on Raspberry Pi Zero/Zero W/3B+/4B.

Sensirion SPS30

Introduction

Python-based driver for Sensirion SPS30 particulate matter sensor. Tested on Raspberry Pi Zero/Zero W/3B+/4B.

Wiring

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

I2C Interface

  Sensor Pins                                 Raspberry Pi Pins
.-------.-----.                             .----------.---------.
| 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 |
'-------'-----'                             '----------'---------'

Example

Default parameters of SPS30 class

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

import sys
import json
from time import sleep
from sps30 import SPS30


if __name__ == "__main__":
    pm_sensor = SPS30()
    print(f"Firmware version: {pm_sensor.firmware_version()}")
    print(f"Product type: {pm_sensor.product_type()}")
    print(f"Serial number: {pm_sensor.serial_number()}")
    print(f"Status register: {pm_sensor.read_status_register()}")
    print(
        f"Auto cleaning interval: {pm_sensor.read_auto_cleaning_interval()}s")
    print(f"Set auto cleaning interval: {pm_sensor.write_auto_cleaning_interval_days(2)}s")
    pm_sensor.start_measurement()

    while True:
        try:
            print(json.dumps(pm_sensor.get_measurement(), indent=2))
            sleep(2)

        except KeyboardInterrupt:
            print("Stopping measurement...")
            pm_sensor.stop_measurement()
            sys.exit()

Output data format

{
  "sensor_data": {
    "mass_density": {
      "pm1.0": 1.883,
      "pm2.5": 3.889,
      "pm4.0": 6.232,
      "pm10": 6.7
    },
    "particle_count": {
      "pm0.5": 1.302,
      "pm1.0": 4.595,
      "pm2.5": 7.326,
      "pm4.0": 7.864,
      "pm10": 7.967
    },
    "particle_size": 1.63,
    "mass_density_unit": "ug/m3",
    "particle_count_unit": "#/cm3",
    "particle_size_unit": "um"
  },
  "timestamp": 1630217804
}

Dependencies

None

sps30's Issues

Extension : write_auto_cleaning_interval_days() function

In sps30.py :
def write_auto_cleaning_interval_days(self, days: int) -> int:
seconds = days * 86400 # 1day = 86400sec
interval = []
interval.append((seconds & 0xff000000) >> 24)
interval.append((seconds & 0x00ff0000) >> 16)
interval.append((seconds & 0x0000ff00) >> 8)
interval.append(seconds & 0x000000ff)
data = CMD_AUTO_CLEANING_INTERVAL
data.extend([interval[0], interval[1]])
data.append(self.crc_calc(data[2:4]))
data.extend([interval[2], interval[3]])
data.append(self.crc_calc(data[5:7]))
self.i2c.write(data)
sleep(0.05)
return self.read_auto_cleaning_interval()

Usage (example.py):
...
pm_sensor = SPS30(3) #Im using i3c_bus3
...
print(f"Set auto cleaning interval: {pm_sensor.write_auto_cleaning_interval_days(2)}s")

I'm using your code for the SPS30 which is really cool but I have a problem.

I'm hoping you can help me with an error running example.py. I get this error:

Serial number: CCC69E8DCEAD8B5F
Status register: {'speed_status': 'ok', 'laser_status': 'ok', 'fan_status': 'ok'}
Traceback (most recent call last):
File "/home/pi/Source/SPS30/example.py", line 13, in
print(f"Auto cleaning interval: {pm_sensor.read_auto_cleaning_interval()}s")
File "/home/pi/Source/SPS30/sps30.py", line 167, in read_auto_cleaning_interval
data = self.i2c.read(NBYTES_AUTO_CLEANING_INTERVAL)
File "/home/pi/Source/SPS30/i2c/i2c.py", line 21, in read
return list(self.fr.read(nbytes))
OSError: [Errno 121] Remote I/O error

If I remove/comment the line print(f"Auto cleaning interval: {pm_sensor.read_auto_cleaning_interval()}s")line I get readings as expected:

Do you have any thoughts on what might be happening?

Here is the code I'm using which is the example.py file included in the download:

import sys
import json
from time import sleep
from sps30 import SPS30

if name == "main":
pm_sensor = SPS30()
print(f"Firmware version: {pm_sensor.firmware_version()}")
print(f"Product type: {pm_sensor.product_type()}")
print(f"Serial number: {pm_sensor.serial_number()}")
print(f"Status register: {pm_sensor.read_status_register()}")
#print(f"Auto cleaning interval: {pm_sensor.read_auto_cleaning_interval()}s")
pm_sensor.start_measurement()

while True:
    try:
        print(json.dumps(pm_sensor.get_measurement(), indent=2))
        sleep(2)

    except KeyboardInterrupt:
        print("Stopping measurement...")
        pm_sensor.stop_measurement()
        sys.exit()

Thanks advance,
Walt

ieee754 conversion

Hi.

I think there is a problem with your ieee754 conversion function. I observed that particulate size smaller than 1 um is still displayed as 1+ um sized particle. We are talking about the case when the exponent is < 0. In that case the resulting number should be divided with the power of 2, of the absolute value of the exponent. I hope it is clear what i mean to say, and am i right. :) I modified the sps30.py (ieee754_number_conversion function) in the way seen below:

exp = 0 if exp < 0 else exp ------ would be

     divider = 0
     if (exp < 0):
         divider = abs(exp)
         exp = 0 

return round((((-1)**(sign) * real) + dec), 3) ------ would be

     if (divider == 0):
         return (round((((-1)**(sign) * real) + dec), 3))
     else:
         return ((round((((-1)**(sign) * real) + dec), 3) / pow(2, divider)))

Probably there is a more elegant way to do this, but it is working.
Regards,
Laszlo

Issue with i2c setup

Hello

I am trying to use this cool library on a raspberrypi 4b with circuitpython. I have two other sensors connected on the i2c working ok. My circuitpython i2c interface is setup like so:

import json
import socket
import time

import adafruit_scd30
import adafruit_sht4x
import board

i2c = board.I2C() 
sht = adafruit_sht4x.SHT4x(i2c)
scd = adafruit_scd30.SCD30(i2c)

So adding the code for sps30 looks like this:

import json
import socket
import time

import adafruit_scd30
import adafruit_sht4x
import board

import sys  # this is not working - greyed out
from sps30 import SPS30

i2c = board.I2C() 
sht = adafruit_sht4x.SHT4x(i2c)
scd = adafruit_scd30.SCD30(i2c)

# sps dust sensor setup
if __name__ == "__main__":
    pm_sensor = SPS30(i2c)
    print(f"Firmware version: {pm_sensor.firmware_version()}")
    print(f"Product type: {pm_sensor.product_type()}")
    print(f"Serial number: {pm_sensor.serial_number()}")
    print(f"Status register: {pm_sensor.read_status_register()}")
    print(
        f"Auto cleaning interval: {pm_sensor.read_auto_cleaning_interval()}s")
    print(f"Set auto cleaning interval: {pm_sensor.write_auto_cleaning_interval_days(2)}s")
    pm_sensor.start_measurement()

This throws an error, because I guess its referencing a different I2C setup in your files?

Traceback (most recent call last):
  File "/opt/piMonitor_env/airmonitor.py", line 111, in <module>
    pm_sensor = SPS30(i2c)
  File "/opt/piMonitor_env/sps30.py", line 50, in __init__
    self.i2c = I2C(bus, address)
  File "/opt/piMonitor_env/i2c/i2c.py", line 11, in __init__
    self.fr = io.open("/dev/i2c-"+str(bus), "rb", buffering=0)
FileNotFoundError: [Errno 2] No such file or directory: '/dev/i2c-<busio.I2C object at 0x7f86cf22b0>'

Any ideas how to use circuitpythons i2c setup?