Support Sensirion SPS30 Particulate Matter Sensor (Sparkfun SEN-15103)

[mew-cx]

I'm looking for a circuitpython library for the Sensirion SPS30, sold by Sparkfun:

• https://www.sensirion.com/en/environmental-sensors/particulate-matter-sensors-pm25/
• https://www.sparkfun.com/products/15103

I haven't found one, so planning to start development myself:

• https://github.com/mew-cx/CircuitPython_SPS30

These seem good places to borrow code:

• https://github.com/Sensirion/embedded-uart-sps (nice C/C++ code, I'd prefer circuitpython)
• https://github.com/adafruit/Adafruit_CircuitPython_PM25
• https://github.com/adafruit/Adafruit_CircuitPython_SGP30
• https://github.com/adafruit/Adafruit_CircuitPython_SGP40

[tannewt]

Great! Thanks for working on it. Another good reference for standard sensor property names and units is: https://circuitpython.readthedocs.io/en/latest/docs/design_guide.html#sensor-properties-and-units

[tannewt]

Library creation is covered here: https://learn.adafruit.com/creating-and-sharing-a-circuitpython-library

[kevinjwalters]

@mew-cx How far did you get with this? Were you thinking UART or i2c or both?

>>> ["{:02x}".format(x) for x in i2c.scan()]
['08', '23', '69', '76']

[kevinjwalters]

https://github.com/Sensirion/embedded-sps Might be useful too, for (i2c) comparison.

[mew-cx]

Hi @kevinjwalters, thanks for reaching out. It seems that creating this issue basically caused my time to work on it to evaporate. However, wildfire season is fast approaching, so I'll prob be reprioritizing.

My interest and work to date have been on the UART side. I think I saw on the SparkFun site the UART interface provided more complete data than I2C, tho I haven't confirmed.

I'm a C++ guy, haven't done much w Python, this was a learning project. I have the Sensirion code tweaked a bit, the firmware in my device is newer than their example code.

I'd certainly welcome any collaboration.

[kevinjwalters]

I'm certainly familiar with the finite amount of time issue! I saw the SparkFun comment too on https://www.sparkfun.com/products/15103 too (retrieved 25-May-2021):

Sensirion has written drivers for both the UART protocol and I2C. Unfortunately we've found the I2C is limited to only mass concentrations (not number concentrations) using the Arduino platform. So if you plan to use this sensor with an Arduino, use the UART interface. Both interfaces are described in their datasheet.

Re-reading that I now wonder if it's specifically about Sensirion's drivers and not the physical device? Hopefully, that's the case.

I have a few more days of code tidying and documentating for my current project then I'll have a look at the SPS-30. I'll keep this ticket updated with any work.

[kevinjwalters]

FYI, I've got about half of an i2c library now:

Adafruit CircuitPython 6.2.0 on 2021-04-05; Adafruit Feather nRF52840 Express with nRF52840
>>>
>>> import board
>>> import adafruit_sps30.sps30_i2c
>>> i2c = board.I2C()
>>> spsi2c = adafruit_sps30.sps30_i2c.SPS30_I2C(i2c)
>>> spsi2c.fw_version
(2, 2)
>>> spsi2c.read()
{'particles 40um': 51, 'particles 10um': 49, 'pm10 standard': 6, 'pm100 standard': 9, 'pm25 standard': 8, 'particles 25um': 50, 'particles 100um': 51, 'particles 05um': 41, 'tps': 576, 'pm40 standard': 9}
>>> spsi2c.read()
{'particles 40um': 41, 'particles 10um': 41, 'pm10 standard': 5, 'pm100 standard': 6, 'pm25 standard': 6, 'particles 25um': 41, 'particles 100um': 41, 'particles 05um': 35, 'tps': 632, 'pm40 standard': 6}

I don't have an immediate need for the uart side of things but there's some degree of overlap.

Are there any existing Adafruit implementations of Sensirion's SHDLC protocol?

[ladyada]

not that we know of! we've only used i2c? good luck!

[kevinjwalters]

I've just noticed @Jacksonbaker323 has an i2c library https://github.com/Jacksonbaker323/CircuitPython_SPS30/ - that one doesn't follow the style of https://github.com/adafruit/Adafruit_CircuitPython_PM25

I'm tidying the code for my library in the mold of the Adafruit_CircuitPython_PM25 library, I've not implemented the UART version yet...

[kevinjwalters]

Has the basic functionality for i2c: https://github.com/kevinjwalters/Adafruit_CircuitPython_SPS30

[kevinjwalters]

The odd comment on Sparkfun site

Sensirion has written drivers for both the UART protocol and I2C. Unfortunately we've found the I2C is limited to only mass concentrations (not number concentrations) using the Arduino platform. So if you plan to use this sensor with an Arduino, use the UART interface. Both interfaces are described in their datasheet.

might be explained by this

https://github.com/Sensirion/arduino-sps/blob/df6346ab6485410963adf24164e955456383dd81/examples/sps30/sps30.ino#L44-L51 which cites https://github.com/Sensirion/arduino-sps#esp8266-partial-legacy-support

[mew-cx]

Hi @kevinjwalters I have some time for the UART implementation. I see you have a repo going, I'll have a look. Just curious: do you have SHDLC encapsulated?

[kevinjwalters]

No, I've focussed on i2c and I've not done any SHDLC but I'd imagine there's a lot of code out there for inspiration. Might be worth sticking to a small code / lowish memory approach to make the library useful on the low end boards like SAMD21.

On i2c front my SPS30 works well for returing 16 bit integers but I can't get it (running V2.2 firmware) to go into floating point mode. I'm probably doing something daft...