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

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")

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?

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