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0.6.1 SHT85
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‎libraries/SHT85/CHANGELOG.md

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@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
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and this project adheres to [Semantic Versioning](http://semver.org/).
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## [0.6.1] - 2025-04-28
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- add **clearStatus()**, kudos to Elbandi (see SHT31)
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- update readme.md
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- add example SHT30_test_address.ino
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- minor edits
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## [0.6.0] - 2023-12-09
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- refactor API, move parameters from begin() to constructor
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- update readme.md

‎libraries/SHT85/LICENSE

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MIT License
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Copyright (c) 2021-2024 Rob Tillaart
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Copyright (c) 2021-2025 Rob Tillaart
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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

‎libraries/SHT85/README.md

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@@ -37,40 +37,22 @@ Always check datasheet before connecting!
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```
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The SHT85 sensors should work (I2C) up to 1000 KHz.
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During tests with an Arduino UNO it stopped between 500 - 550 KHz.
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So to be safe I recommend not to use the sensor above 400 KHz.
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Also the differences in read time becomes quite small. (max 15% gain).
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See indicative output example sketch.
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SPS (= samples per second) are added later.
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| I2C speed | read ms | SPS | notes |
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|:---------:|:-------:|:-----:|:--------|
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| 50 KHz | 6.60 | 123 |
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| 100 KHz | 5.11 | 140 | default
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| 150 KHz | 4.79 | |
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| 200 KHz | 4.64 | 140 |
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| 250 KHz | 4.56 | |
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| 300 KHz | 4.50 | 164 |
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| 350 KHz | 4.47 | |
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| 400 KHz | 4.45 | 164 |
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| 450 KHz | 4.43 | |
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| 500 KHz | 4.42 | 163 |
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| 550 KHz | ---- | | fail
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### 0.6.0 Breaking change
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At 10% load the SHT85 can be used to make about 10 - 15 SPS.
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Version 0.6.0 introduced a breaking change.
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You cannot set the pins in **begin()** any more.
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This reduces the dependency of processor dependent Wire implementations.
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The user has to call **Wire.begin()** and can optionally set the Wire pins
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before calling **begin()**.
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#### Compatibility
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### Compatibility
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The SHT85 is protocol compatible with the SHT3x series.
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Main difference is the accuracy and the SHT85 only has address 0x44.
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Main difference is the accuracy and the SHT85 only has one address 0x44.
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Compare the data sheets to see all differences.
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Accuracy table:
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Accuracy table
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| Sensor | Temperature | Humidity | Verified }
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|:--------:|:-------------:|:----------:|:----------:|
@@ -84,7 +66,36 @@ Note: The SHT40, SHT41 and SHT45 are not protocol compatible with SHT3x and SHT8
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The SHT4x series is slightly faster than the SHT3x series.
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#### Multiple SHT85
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### I2C performance
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The SHT85 sensors should work (I2C) up to 1000 KHz.
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During tests with an Arduino UNO it stopped between 500 - 550 KHz.
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So to be safe I recommend not to use the sensor above 400 KHz.
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Also the differences in read time becomes quite small. (max 15% gain).
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See indicative output example sketch.
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SPS (= samples per second) are added later.
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| I2C speed | read ms | SPS | notes |
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|:-----------:|:---------:|:-----:|:--------|
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| 50 KHz | 6.60 | 123 |
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| 100 KHz | 5.11 | 140 | default
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| 150 KHz | 4.79 | |
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| 200 KHz | 4.64 | 140 |
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| 250 KHz | 4.56 | |
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| 300 KHz | 4.50 | 164 |
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| 350 KHz | 4.47 | |
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| 400 KHz | 4.45 | 164 |
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| 450 KHz | 4.43 | |
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| 500 KHz | 4.42 | 163 |
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| 550 KHz | ---- | | fail
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At 10% load the SHT85 can be used to make about 10 - 15 SPS.
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### Multiple SHT85
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The SHT3x comes with two I2C address options, 0x44 and 0x45.
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The SHT85 only has 0x44 as I2C address, so it is not possible to have more than
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a software I2C (below) or an I2C multiplexer e.g. https://github.com/RobTillaart/TCA9548
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#### 0.6.0 Breaking change
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### I2C multiplexing
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Sometimes you need to control more devices than possible with the default
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address range the device provides.
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This is possible with an I2C multiplexer e.g. TCA9548 which creates up
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to eight channels (think of it as I2C subnets) which can use the complete
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address range of the device.
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Drawback of using a multiplexer is that it takes more administration in
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your code e.g. which device is on which channel.
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This will slow down the access, which must be taken into account when
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deciding which devices are on which channel.
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Also note that switching between channels will slow down other devices
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too if they are behind the multiplexer.
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- https://github.com/RobTillaart/TCA9548
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Version 0.6.0 introduced a breaking change.
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The parameters from begin() moved to the constructor.
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You cannot set the pins in **begin()** any more.
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This reduces the dependency of processor dependent Wire implementations.
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The user has to call **Wire.begin()** and can optionally set the Wire pins
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before calling **begin()**.
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### Related
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#### Related
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SHT series temperature sensors
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- https://github.com/RobTillaart/SHT2x
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- https://github.com/RobTillaart/SHT31
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- https://github.com/RobTillaart/SHT31 Sensirion humidity / temperature sensor
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- https://github.com/RobTillaart/SHT31_SW = softWire based I2C.
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- https://github.com/RobTillaart/SHT31_SWW = softWire based I2C.
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- https://github.com/RobTillaart/SHT85 Sensirion humidity / temperature sensor
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- https://github.com/RobTillaart/tinySHT2x
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Other temperature sensors
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- https://github.com/RobTillaart/DHTNew DHT11/22 etc
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- https://github.com/RobTillaart/DHTStable DHT11/22 etc
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- https://github.com/RobTillaart/DHT_Simulator
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- https://github.com/RobTillaart/DS18B20_INT OneWire temperature sensor
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- https://github.com/RobTillaart/DS18B20_RT OneWire temperature sensor
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An elaborated library for the SHT31 sensor can be found here
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- https://github.com/hawesg/SHT31D_Particle_Photon_ClosedCube
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Dewpoint, heatindex, related functions and conversions.
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- https://github.com/RobTillaart/Temperature
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Other, including Dewpoint, heatindex, related functions and conversions.
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I2C multiplexer
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- https://github.com/RobTillaart/TCA9548
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- https://www.kandrsmith.org/RJS/Misc/Hygrometers/calib_many.html (interesting)
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- https://github.com/RobTillaart/Temperature (conversions, dewPoint, heat index etc.)
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## Interface
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#include "SHT85.h"
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```
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#### Constructor
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### Constructor
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- **SHT(uint8_t address, TwoWire \*wire = &Wire)** constructor of the base class.
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Note that **getType()** will return 0.
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- **uint8_t getType()** returns numeric part of sensor type.
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Returns 0 for the base class.
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- **bool begin()** Returns false if device address is incorrect or device cannot be reset.
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- **uint8_t getAddress()** returns address set in constructor.
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- **uint8_t getAddress()** returns address set in the constructor.
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#### Status
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### Status
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- **bool isConnected()** checks if address of the sensor is reachable over I2C. Returns false if not connected.
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- **uint16_t readStatus()** details see datasheet and **Status fields** below.
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- **uint16_t readStatus()** returns bit mask, details see **Status fields** below (and datasheet).
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- **bool clearStatus()** clear status register, see **Status fields** below.
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- **uint32_t lastRead()** in milliSeconds since start of program.
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- **bool reset(bool hard = false)** resets the sensor, soft reset by default. Returns false if fails.
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- **bool reset(bool hard = false)** resets the sensor, soft reset by default. Returns false if call fails.
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#### Synchronous read
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### Synchronous read
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- **bool read(bool fast = true)** blocks 4 (fast) or 15 (slow) milliseconds + actual read + math.
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Reads both the temperature and humidity from the device.
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Note: the medium level is not supported (yet).
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#### Asynchronous read
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### Asynchronous read
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See async example for usage.
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This function is used to check if the request is too long ago.
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#### Temperature and humidity
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### Temperature and humidity
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Note that the temperature and humidity values are recalculated on every call to **getHumidity()** and **getTemperature()**.
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If you're worried about the extra cycles, you should make sure to cache these values or only request them after
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```
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#### Temperature and humidity offset
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### Temperature and humidity offset
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Default the offset is zero for both temperature and humidity.
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These functions allows one to adjust them a little. Note there is no limit to the offset so one can use huge values. This allows to use an offset of 273.15 effectively creating **°Kelvin** instead of Celsius.
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These functions allows one to adjust them a little.
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Note: there is no limit to the offset so one can use huge values.
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This allows to use an offset of 273.15 effectively creating degrees **Kelvin** instead of **Celsius**.
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Note: the offset is defined in degrees Celsius.
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To set an offset in degrees Fahrenheit, multiply the Fahrenheit offset with 0.55555556 to get Celsius steps (divide by 1.8 is slower).
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So an offset of 4 °F becomes 2.2222 °C.
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Note: the offset for humidity may cause boundary issues (below 0 and above 100)
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- **void setTemperatureOffset(float offset = 0)** set the offset in °C, default is zero removing the offset. The library converts this internally
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- **void setTemperatureOffset(float offset = 0)** set the offset in °C, default is zero removing the offset.
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The library converts this internally
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- **float getTemperatureOffset()** returns the set offset in °C.
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- **void setHumidityOffset(float offset = 0)** set the offset, default is zero removing the offset.
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- **float getHumidityOffset()** returns the set offset.
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#### Error interface
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### Error interface
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- **int getError()** returns last set error flag and clear it.
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Be sure to clear the error flag by calling **getError()** before calling
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any command as the error flag could be from a previous command.
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| Error | Symbolic | Description |
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|:-------:|:--------------------------|:-------------------------------|
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| 0x00 | SHT_OK | no error |
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| 0x81 | SHT_ERR_WRITECMD | I2C write failed |
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| 0x82 | SHT_ERR_READBYTES | I2C read failed |
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| 0x83 | SHT_ERR_HEATER_OFF | Could not switch off heater |
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| 0x84 | SHT_ERR_NOT_CONNECT | Could not connect |
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| 0x85 | SHT_ERR_CRC_TEMP | CRC error in temperature |
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| 0x86 | SHT_ERR_CRC_HUM | CRC error in humidity |
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| 0x87 | SHT_ERR_CRC_STATUS | CRC error in status field |
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| 0x88 | SHT_ERR_HEATER_COOLDOWN | Heater need to cool down |
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| 0x89 | SHT_ERR_HEATER_ON | Could not switch on heater |
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| 0x8A | SHT_ERR_SERIAL | Could not read serial number |
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| 0x00 | SHT_OK | no error |
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| 0x81 | SHT_ERR_WRITECMD | I2C write failed |
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| 0x82 | SHT_ERR_READBYTES | I2C read failed |
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| 0x83 | SHT_ERR_HEATER_OFF | Could not switch off heater |
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| 0x84 | SHT_ERR_NOT_CONNECT | Could not connect |
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| 0x85 | SHT_ERR_CRC_TEMP | CRC error in temperature |
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| 0x86 | SHT_ERR_CRC_HUM | CRC error in humidity |
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| 0x87 | SHT_ERR_CRC_STATUS | CRC error in status field |
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| 0x88 | SHT_ERR_HEATER_COOLDOWN | Heater need to cool down |
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| 0x89 | SHT_ERR_HEATER_ON | Could not switch on heater |
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| 0x8A | SHT_ERR_SERIAL | Could not read serial number |
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#### Heater interface
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### Heater interface
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**WARNING:** Do not use heater for long periods.
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This value is truncated to max 180 seconds.
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- **uint8_t getHeatTimeout()** returns the value set.
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- **bool heatOn()** switches the heat cycle on if not already on.
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Returns false if this fails, setting error to **SHT_ERR_HEATER_COOLDOWN**
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Returns false if the call fails, setting error to **SHT_ERR_HEATER_COOLDOWN**
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or to **SHT_ERR_HEATER_ON**.
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- **bool heatOff()** switches the heat cycle off.
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## Status fields
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| BIT | Description | value | notes |
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|:------|:---------------------------|:--------|:--------|
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| 15 | Alert pending status | 0 | no pending alerts
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| | | 1 | at least one pending alert - default
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| 14 | Reserved | 0 |
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| 13 | Heater status | 0 | Heater OFF - default
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| | | 1 | Heater ON
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| 12 | Reserved | 0 |
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| 11 | Humidity tracking alert | 0 | no alert - default
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| | | 1 | alert
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| 10 | Temperature tracking alert | 0 | no alert - default
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| | | 1 | alert
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| 9-5 | Reserved | 00000 | reserved
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| 4 | System reset detected | 0 | no reset since last ‘clear status register’ command
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| | | 1 | reset detected (hard or soft reset command or supply fail) - default
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| 3-2 | Reserved | 00 |
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| 1 | Command status | 0 | last command executed successfully
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| | | 1 | last command not processed. Invalid or failed checksum
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| 0 | Write data checksum status | 0 | checksum of last write correct
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| | | 1 | checksum of last write transfer failed
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#### SHT85 specific
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| BIT | Description | value | notes |
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|:------|:-----------------------------|:--------|:--------|
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| 15 | Alert pending status | 0 | no pending alerts
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| | | 1 | at least one pending alert - default
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| 14 | Reserved | 0 |
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| 13 | Heater status | 0 | Heater OFF - default
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| | | 1 | Heater ON
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| 12 | Reserved | 0 |
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| 11 | Humidity tracking alert | 0 | no alert - default
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| | | 1 | alert
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| 10 | Temperature tracking alert | 0 | no alert - default
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| | | 1 | alert
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| 9-5 | Reserved | 00000 | reserved
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| 4 | System reset detected | 0 | no reset since last ‘clear status register’ command
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| | | 1 | reset detected (hard or soft reset command or supply fail) - default
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| 3-2 | Reserved | 00 |
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| 1 | Command status | 0 | last command executed successfully
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| | | 1 | last command not processed. Invalid or failed checksum
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| 0 | Write data checksum status | 0 | checksum of last write correct
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| | | 1 | checksum of last write transfer failed
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**bool clearStatus()** clears 15, 11, 10 and 4.
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### SHT85 specific
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- **uint32_t GetSerialNumber()** Returns a 32 bit unique serial number.
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This command seems to be timing sensitive, it uses a delay of 500us
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## Future
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#### Must
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- improve documentation.
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Thank you,
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