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Merge pull request #8 from /issues/7
Update documentation MH-Z19C
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‎.auto-build.sh

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#
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# MIT License
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#
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# Copyright (c) 2020-2022 Erriez
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# Copyright (c) 2020-2023 Erriez
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal

‎LICENSE

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MIT License
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Copyright (c) 2020-2022 Erriez
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Copyright (c) 2020-2023 Erriez
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal

‎README.md

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### Pins
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WARNING: The pins between MH-Z19B and MH-Z19C are different. See tables below:
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```c++
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// MH-Z19B front connector
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// __ _______
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// +------------------+
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// | |
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// | . . . . . . . |
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// | 1 2 3 4 5 6 7 |
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// +------------------+
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//
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// Pin 1: Yellow None
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// Pin 2: Green UART (TXD) TTL Level Data Output -> TO RXD
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// Pin 3: Blue UART(RXD) TTL Level Data Input -> TO TXD
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// Pin 4: Red Positive Power Supply (Vin +5V)
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// Pin 5: Black Negative Power Supply (GND)
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// Pin 6: White None
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// Pin 7: Brown Analog Output Vo (Not used)
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// MH-Z19B front connector:
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// Pin 1: Yellow None
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// Pin 2: Green UART (TXD) TTL Level Data Output -> TO RXD
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// Pin 3: Blue UART (RXD) TTL Level Data Input -> TO TXD
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// Pin 4: Red Positive Power Supply (Vin +5V)
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// Pin 5: Black Negative Power Supply (GND)
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// Pin 6: White None
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// Pin 7: Brown Analog Output Vo (Not used)
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//
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// MH-Z19C front connector:
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// Pin 1: PWM
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// Pin 2: UART (TXD) TTL Level data output -> TO RXD
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// Pin 3: UART (RXD) TTL Level data input -> TO TXD
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// Pin 4: Positive Power Supply (Vin +5V)
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// Pin 5: Negative Power Supply (GND)
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// Pin 6: Analog Output Vo
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// Pin 7: HD (Hand-operated calibration)
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//
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// The following ESP8266 pins are reserved:
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// TX/RX: Serial (in use)
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- [Online HTML](https://erriez.github.io/ErriezMHZ19B)
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- [Doxygen PDF](https://github.com/Erriez/ErriezMHZ19B/blob/gh-pages/ErriezMHZ19B.pdf)
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- [Datasheet PDF](https://github.com/Erriez/ErriezMHZ19B/blob/master/extras/mh-z19b-co2-ver1_0.pdf)
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- [MH-Z19B datasheet PDF](https://github.com/Erriez/ErriezMHZ19B/blob/master/extras/mh-z19b-co2-ver1_0.pdf)
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- [MH-Z19C datasheet PDF](https://github.com/Erriez/ErriezMHZ19B/blob/master/extras/mh-z19c-co2-ver1_21.pdf)
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## CO2 Concentrations
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For simplicity, this library uses the terminology `Automatic Calibration` which is identical to the
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`ABC (Automatic Baseline Correction) logic on/off` mentioned in the datasheet.
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### 2. Manual Calibration (400ppm)
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### 2. Manual ZERO Calibration (400ppm)
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Procedure for manual calibration at 400ppm:
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Now the sensor is calibrated. Repeat the sequence more often for higher accuracy.
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### 3. Manual Calibration (SPAN)
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### 3. MH-Z19B only: Manual SPAN Calibration
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The SPAN point calibration procedure is not implemented in this library as it requires special
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calibration equipment. This functionality is not available in MH-Z19C.
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The datasheet also mentions a command `0x88 Span Point Calibration`. The calibration procedure is
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not clear and therefore not implemented in this library.
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### 4. MH-Z19C only: Hand-operated calibration
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Procedure according to the MH-Z19C datasheet:
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- Connect module’s HD pin to low level(0V), lasting for 7 seconds at least.
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- Before calibrating the zero point, please ensure that the sensor is stable for more than 20
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minutes at 400ppm ambient environment.
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- The application is responsible to control the external MH-Z19C HD pin and is not available on
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the MH-Z19B.
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## MH-Z19B API
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## MH-Z19B/C API
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**Initialization Software Serial**
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‎examples/ErriezMHZ19B7SegmentDisplay/ErriezMHZ19B7SegmentDisplay.ino

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/*
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* MIT License
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*
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* Copyright (c) 2020-2022 Erriez
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* Copyright (c) 2020-2023 Erriez
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal

‎examples/ErriezMHZ19BESP8266MQTT/ErriezMHZ19BESP8266MQTT.ino

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/*
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* MIT License
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*
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* Copyright (c) 2020-2022 Erriez
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* Copyright (c) 2020-2023 Erriez
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal

‎examples/ErriezMHZ19BGettingStarted/ErriezMHZ19BGettingStarted.ino

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/*
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* MIT License
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*
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* Copyright (c) 2020-2022 Erriez
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* Copyright (c) 2020-2023 Erriez
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal

‎examples/ErriezMHZ19BSerialPlottter/ErriezMHZ19BSerialPlottter.ino

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/*
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* MIT License
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*
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* Copyright (c) 2020-2022 Erriez
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* Copyright (c) 2020-2023 Erriez
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal

‎extras/mh-z19c-co2-ver1_21.pdf

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‎src/ErriezMHZ19B.cpp

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/*
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* MIT License
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*
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* Copyright (c) 2020-2022 Erriez
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* Copyright (c) 2020-2023 Erriez
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal

‎src/ErriezMHZ19B.h

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/*
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* MIT License
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*
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* Copyright (c) 2020-2022 Erriez
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* Copyright (c) 2020-2023 Erriez
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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#define MHZ19B_CMD_SET_AUTO_CAL 0x79 //!< Command set auto calibration on/off
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#define MHZ19B_CMD_READ_CO2 0x86 //!< Command read CO2 concentration
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#define MHZ19B_CMD_CAL_ZERO_POINT 0x87 //!< Command calibrate zero point at 400ppm
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#define MHZ19B_CMD_CAL_SPAN_PIONT 0x88 //!< Command calibrate span point (NOT IMPLEMENTED)
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#define MHZ19B_CMD_CAL_SPAN_POINT 0x88 //!< Command calibrate span point (NOT IMPLEMENTED)
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#define MHZ19B_CMD_SET_RANGE 0x99 //!< Command set detection range
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// Not documented commands

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