Arduino library for COZIR range CO2 sensors.
The COZIR library is experimental as not all functionality is tested. The polling mode as used in the examples is tested in the past by DirtGambit. CO2meter.com sponsored a COZIR GC0034 to start hands on testing (2022-02). This sensor does not support all commands, but as the pattern of the commands is similar the non-tested are expected to work as well.
This version of the library supports only the Serial interface. Preferred is a hardware Serial port to connect the sensor but software Serial does work too.
The library (since 0.3.4) a separate class to parse the STREAMING data. See COZIRParser below. The COZIR class is focussed on polling and sending commands.
- Read the datasheet before using this library. It helps to understand the working of the COZIR sensor.
- Be aware that not all microprocessors have a SoftwareSerial library or one limited in performance. Polling at 9600 baud can be pretty blocking.
- the hardware serial based examples needs to be run on a MEGA or a Teensy, at least a board with more than one Serial port.
- If the device is in CZR_COMMAND mode it does not respond too polling calls. It needs to be set to CZR_POLLING mode.
- Not all COZIR devices support all calls of this library.
- https://emariete.com/en/sensor-co2-mh-z19b/
- https://emariete.com/en/sensor-co2-low-consumption-mh-z1311a-winsen/
- https://revspace.nl/MHZ19
- https://www.co2.earth/ - current outdoor CO2 level can be used for calibrating.
- https://keelingcurve.ucsd.edu/ - historical outdoor CO2 level.
- https://github.com/RobTillaart/ACD10
- https://github.com/RobTillaart/MTP40C
- https://github.com/RobTillaart/MTP40F
- https://github.com/RobTillaart/Cozir
#include "Cozir.h"Read the datasheet (again).
- COZIR(Stream * str) constructor, gets a serial stream as reference.
- void init() sets operatingMode to CZR_POLLING
- bool isInitialized() returns true if enough time has passed after the call to init() for the sensor. The sensor needs a few seconds to get correct values.
- void setOperatingMode(uint8_t mode) set the operating mode either to CZR_COMMAND, CZR_POLLING or CZR_STREAMING
- uint8_t getOperatingMode() returns the mode set, CZR_STREAMING is the factory default. Please note that init() sets the operating mode to CZR_POLLING.
The COZIR CO2 sensors all support:
- uint32_t CO2() returns the CO2 concentration in PPM (!! might need PPMfactor).
- uint16_t getPPMFactor() returns 1, 10, 100. Normally the value returned is 1 but one should check at the first read and when there is a big jump in values returned. Also when time interval between reads is large it might be useful to check the PPM factor.
Some COZIR sensors also support:
- float celsius() returns temperature of the sensor.
- float fahrenheit() idem, 'wrapper' around celsius()
- float humidity() idem, 'wrapper' around celsius()
- float light() idem.
Read datasheet before using these functions:
- uint16_t fineTuneZeroPoint(uint16_t v1, uint16_t v2)
- uint16_t calibrateFreshAir() typically 400 PPM.
- uint16_t calibrateNitrogen()
- uint16_t calibrateKnownGas(uint16_t value)
Following 3 functions are NOT RECOMMENDED by the datasheet. Feel free to uncomment in the code and use at your own risk. Read datasheet before using these functions:
- uint16_t calibrateManual(uint16_t value)
- uint16_t setSpanCalibrate(uint16_t value)
- uint16_t getSpanCalibrate()
use with care, read datasheet before use.
| value | meaning |
|---|---|
| 0 | Special, see datasheet |
| 1 | fast, shows every single sample, raw, can be noisy |
| 32 | default, good average |
| 255 | very slow, max smoothed |
- void setDigiFilter(uint8_t value) The larger the value the more smoothed the signal is. Larger values also means that the output does not follow fast changes. So depending on your needs you need to find an optimal value for the project. It might even so that you alternate between smooth and fast or adapt depending on the actual CO2 value.
- uint8_t getDigiFilter() returns set value.
Warning: hardware serial is needed / recommended to improve the capture of all output correctly.
- void setOutputFields(uint16_t fields) Sets the fields in the output stream as a 16 bit mask. See table below.
- void clearOutputFields() clears all the fields.
- uint16_t getOutputFields() returns the 16 bit mask of set output fields.
- bool inOutputFields(uint16_t field) returns true if the field is set.
- void getRecentFields() After a call to getRecentFields() you must read and parse the serial stream yourself. The internal buffer of this Class cannot handle the possible large output. Lines can be over 100 bytes long!
The fields must be set as a bit mask, the order of the fields in the output is undetermined. So one need to parse the output of the sensor carefully.
Note: NOT all sensors support all fields, check the datasheet of the sensor used.
| Field | Value HEX | Value DEC | Notes |
|---|---|---|---|
| CZR_LIGHT | 0X2000 | 8192 | |
| CZR_HUMIDITY | 0X1000 | 4096 | |
| CZR_FILTLED | 0X0800 | 2048 | |
| CZR_RAWLED | 0X0400 | 1024 | |
| CZR_MAXLED | 0X0200 | 512 | |
| CZR_ZEROPOINT | 0X0100 | 256 | |
| CZR_RAWTEMP | 0X0080 | 128 | |
| CZR_FILTTEMP | 0X0040 | 64 | |
| CZR_FILTLEDSIGNAL | 0X0020 | 32 | |
| CZR_RAWLEDSIGNAL | 0X0010 | 16 | |
| CZR_SENSTEMP | 0X0008 | 8 | |
| CZR_FILTCO2 | 0X0004 | 4 | |
| CZR_RAWCO2 | 0X0002 | 2 | |
| CZR_NONE | 0X0001 | 1 | reset |
| CZR_DEFAULT | 0X0006 | 6 | factory default |
| CZR_HTC | 0X1082 | 4226 | shortcut |
| CZR_ALL | 0X3FFE | 16383 | debug |
Default value is CZR_DEFAULT == 6 == CZR_FILTCO2 + CZR_RAWCO2
Note: not all COZIR devices support EEPROM. Check datasheet for the capabilities of your device.
In 0.3.0 the EEPROM function have been replaced by specific accessor functions. Read datasheet about the addresses and their meaning. Use with care.
- void setAutoCalibrationPreload(uint16_t value)
- uint16_t getAutoCalibrationPreload()
- void setAutoCalibrationInterval(uint16_t value)
- uint16_t getAutoCalibrationInterval()
- void setAutoCalibrationOn()
- void setAutoCalibrationOff()
- bool getAutoCalibration()
- void setAutoCalibrationBackgroundConcentration(uint16_t value)
- uint16_t getAutoCalibrationBackgroundConcentration()
- void setAmbientConcentration(uint16_t value)
- uint16_t getAmbientConcentration()
- void setBufferClearTime(uint16_t value)
- uint16_t getBufferClearTime()
Read datasheet for the details and defaults of sensor at hand.
| Name | Address | Default | Notes |
|---|---|---|---|
| AHHI | 0x00 | ? | reserved |
| ANLO | 0x01 | ? | reserved |
| ANSOURCE | 0x02 | ? | reserved |
| ACINITHI | 0x03 | 87 | |
| ACINITLO | 0x04 | 192 | |
| ACHI | 0x05 | 94 | |
| ACLO | 0x06 | 128 | |
| ACONOFF | 0x07 | 0 | |
| ACPPMHI | 0x08 | 1 | |
| ACPPMLO | 0x09 | 194 | |
| AMBHI | 0x0A | 1 | |
| AMBLO | 0x0B | 194 | |
| BCHI | 0x0C | 0 | |
| BCLO | 0x0D | 8 |
- void getVersionSerial() requests version over serial. The user should read (and parse) the serial output as it can become large. Also the user must reset the operating mode either to CZR_POLLING or CZR_STREAMING
- void getConfiguration() requests configuration over serial. The user should read (and parse) the serial output as it can become large. Also the user must reset the operating mode either to CZR_POLLING or CZR_STREAMING
See examples.
- improve documentation
- COZIR Parser
- separate readme.md
- separate .h and .cpp
- separate repo
- add examples
- example COZIR with I2C LCD display?
- COZIR I2C class for newer generation
~ same functional interface
- multiWire / pin a la PCF8574 lib
- add a setEEPROMFactoryDefault()?
- unknown if all sensors have same values
- build a Arduino COZIR simulator for testing.
- add other sensors underneath?
Class to parse the output of a COZIR sensor in stream mode.
(added in 0.3.4, experimental)
The COZIRparser object has a main function called nextChar(c) It needs to be called with all incoming characters from the sensor.
If a new field is found nextChar() returns the field identifier of the last parsed field (single char) to indicate its value has been updated, otherwise it returns 0. The updated value can be accessed with one of the functions, see cozir.h file.
An example Cozir_stream_parse.ino is added to show how to use this class.
NOTE: to send commands e.g. outputField selection, to the sensor the COZIR class can be used (which is mostly focussed on polling access). Alternatively the user sends the low level commands just as a string over serial. This latter method will save memory especially in a final version of a project.
NOTE: The COZIRparser skips the output of the Y, * and @ command. These are configuration fields and therefore not part of the stream mode fields. Furthermore not all fields these lines produce are understood. So parsing these lines is left to the user for now.
NOTE: The COZIRparser class does not check for missing characters, the range of the fields recognized, or other errors. So the values returned should be handled with care.
Read the datasheet (again).
- C0ZIRParser() constructor
- void init() resets all internal variables to 0 except PPM (set to 1)
- void resetParser() should / could be called if stream from sensor is interrupted for long period, e.g. if there are missing characters. This should prevent the parser to overshoot a value due to concatenating the value of different (interrupted) measurements or FIELDs.
- uint8_t nextChar(char c) all characters coming from the sensor should be send to the parser by means of nextChar(). Default it will return 0 and the FIELD character is a field has been updated. Read Datasheet for the characters used.
The remainder of the interface are getters for the different fields.
- improve documentation
- COZIR Parser a separate readme?
- support splitting output of Y and * command.
- separate parser COZIRParserY()
- separate parser COZIRParserStar()
- separate parser COZIRParser@()
- add examples
- examples for COZIRParser.
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