avsa242 / scd30-spin

Parallax P8X32A/Propeller, P2X8C4M64P/Propeller 2 driver object for the Sensirion SCD30 CO2 sensor

scd30-spin

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This is a P8X32A/Propeller, P2X8C4M64P/Propeller 2 driver object for the Sensirion SCD30 CO2 sensor.

IMPORTANT: This software is meant to be used with the spin-standard-library (P8X32A) or p2-spin-standard-library (P2X8C4M64P). Please install the applicable library first before attempting to use this code, otherwise you will be missing several files required to build the project.

Salient Features

• I2C connection at up to 100kHz (P2, or P1 with PASM engine), or ~30kHz (P1, SPIN engine) (max recommended according to Sensirion is 50kHz)
• Read CO2, Temperature, RH data (IEEE-754 float, or hundredths of unit integer)
• Set measurement interval in seconds
• Sensor data-ready status
• Read sensor firmware version
• Soft-reset
• Set altitude or ambient pressure used to compensate CO2 readings
• Automatic or manual calibration

Requirements

P1/SPIN1:

• spin-standard-library
• 1 extra core/cog for the PASM I2C engine (none if the SPIN I2C engine is used)
• sensor.temp.common.spinh (source: spin-standard-library)
• sensor.rh.common.spinh (source: spin-standard-library)
• sensor.co2.common.spinh (source: spin-standard-library)

P2/SPIN2:

• p2-spin-standard-library
• sensor.temp.common.spin2h (source: p2-spin-standard-library)
• sensor.rh.common.spin2h (source: p2-spin-standard-library)
• sensor.co2.common.spin2h (source: p2-spin-standard-library)

Compiler Compatibility

Processor	Language	Compiler	Backend	Status
P1	SPIN1	FlexSpin (5.9.14-beta)	Bytecode	OK
P1	SPIN1	FlexSpin (5.9.14-beta)	Native code	OK
P1	SPIN1	OpenSpin (1.00.81)	Bytecode	Untested (deprecated)
P2	SPIN2	FlexSpin (5.9.14-beta)	NuCode	FTBFS
P2	SPIN2	FlexSpin (5.9.14-beta)	Native code	OK
P1	SPIN1	Brad's Spin Tool (any)	Bytecode	Unsupported
P1, P2	SPIN1, 2	Propeller Tool (any)	Bytecode	Unsupported
P1, P2	SPIN1, 2	PNut (any)	Bytecode	Unsupported

Limitations

• Requires a build-time change of behavior to the I2C engine; ensure the QUIRK_SCD30 preprocessor flag is added to the build command line

scd30-spin's Issues

Add support for setting temperature scale

Currently the temperature data is only available as Celsius.
Add standard TempScale() method

Add support for (de)activating automatic self-recalibration

The sensor has the ability to automatically self-calibrate. Add support for toggling this setting at runtime.
Add a note stating the first time this feature is enabled:

• the sensor needs to be running continuously for a minimum of 7 days (power can't be removed during this time)
• it needs to be exposed to fresh air for a minimum of 1hr every day during this period
• the result of the calibration is stored on the sensor in non-volatile memory, i.e., it will persist across power loss

Move CRC generation/verification to readReg() and writeReg()

See if this is practical/sensible...it would save on code space since it would all be getting done in the same place. Currently each API method (where applicable) has its own copy of CRC verification and/or generation code.

Add support for altitude compensation

The sensor has the ability to compensate CO2 readings using a specified altitude. Add support for this.

Port to P2/SPIN2

Implemented only in SPIN1 for the Propeller1
Port to SPIN2 for the Propeller2

Add support for setting forced recalibration value

The sensor has the ability to manually set a calibration value to compensate for sensor drift.
Add a note stating the sensor should be run at 2sec measuring interval for at least 2 minutes in a stable environment prior to setting this value. This setting and the automatic re-cal value are mutually exclusive; if this value is set, it will be used, otherwise the automatic re-cal setting will be used.

Add support for pure-spin I2C engine

Add compile-time support for spin I2C engine, for applications that can't spare the extra core for the PASM engine.

Add support for integer-format sensor data

The native output data format from the sensor is IEEE-754 float. There should exist data retrieval methods that return integer values also, so as to be consistent with other sensing drivers.