mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
209 lines
9.2 KiB
Markdown
209 lines
9.2 KiB
Markdown
|
||
[](https://github.com/marketplace/actions/arduino_ci)
|
||
[](https://github.com/RobTillaart/SHT31_SWW/actions/workflows/arduino-lint.yml)
|
||
[](https://github.com/RobTillaart/SHT31_SWW/actions/workflows/jsoncheck.yml)
|
||
[](https://github.com/RobTillaart/SHT31_SWW/issues)
|
||
|
||
[](https://github.com/RobTillaart/SHT31_SWW/blob/master/LICENSE)
|
||
[](https://github.com/RobTillaart/SHT31_SWW/releases)
|
||
[](https://registry.platformio.org/libraries/robtillaart/SHT31_SWW)
|
||
|
||
|
||
# SHT31_SWW
|
||
|
||
Arduino library for the SHT31 temperature and humidity sensor - using **SoftwareWire**.
|
||
|
||
|
||
## Description
|
||
|
||
This **experimental** library features the class SHT31_SWW derived from - https://github.com/RobTillaart/SHT31
|
||
It has the same interface as the SHT31 class so please use that documentation
|
||
as it will be the "leading class".
|
||
|
||
The main difference is that the SHT31_SWW class uses the **SoftwareWire**
|
||
library for communication instead of the **TwoWire** based **Wire** class.
|
||
See SHT31 PR #35.
|
||
|
||
**SoftwareWire** is a software I2C bus library to be able to select other pins
|
||
than the default (AVR) hardware I2C pins (SDA and SCL).
|
||
An important reason to use this version is when you want more than two
|
||
devices on one Arduino.
|
||
|
||
Note: this library is AVR specific.
|
||
|
||
|
||
#### SoftWire vs SoftwareWire
|
||
|
||
The **SoftWire** library is portable, however it could not read (on AVR)
|
||
the SHT85 sensor which is command compatible with the SHT3x.
|
||
The cause is not found yet.
|
||
Therefore a separate repo is created based upon the AVR specific **SoftwareWire**
|
||
see links below.
|
||
If you know a solution to get softWire working on AVR, please let me know.
|
||
|
||
The **SoftwareWire** library is an AVR specific and worked for the SHT85.
|
||
See https://github.com/RobTillaart/SHT31_SW/issues/5
|
||
|
||
|
||
#### SHT3x SHT85 sensors
|
||
|
||
The SHT3x family of sensors should work up to 1 MHz I2C although not tested above 400 MHz.
|
||
|
||
This library should also work for SHT30/35/85 but these are not tested yet.
|
||
|
||
Accuracy table
|
||
|
||
| SENSOR | Temperature | Humidity | works |
|
||
|:--------:|:-------------:|:----------:|:---------------|
|
||
| SHT30 | ~0.3 | 2.0 | (not tested) |
|
||
| SHT31 | ~0.3 | 1.5 | yes |
|
||
| SHT35 | ~0.2 | 1.5 | (not tested) |
|
||
| SHT85 | ~0.2 | 1.5 | yes |
|
||
|
||
|
||
|
||
#### Links
|
||
|
||
These libraries need to be installed to get SHT31_SW working:
|
||
|
||
- https://github.com/RobTillaart/SHT31
|
||
- https://github.com/Testato/SoftwareWire // AVR only
|
||
|
||
Related
|
||
- https://github.com/stevemarple/AsyncDelay
|
||
- https://github.com/stevemarple/SoftWire
|
||
|
||
|
||
## Interface
|
||
|
||
```cpp
|
||
#include "SHT31_SWW.h"
|
||
```
|
||
|
||
Note: The interface is mostly inherited from SHT31 but presented here for completeness.
|
||
|
||
|
||
#### Base interface
|
||
|
||
- **SHT31_SWW()** constructor.
|
||
- **bool begin(uint8_t address, SoftwareWire \*wire = &Wire)** for platforms with multiple I2C buses.
|
||
- **bool begin(SoftwareWire \*wire = &Wire)** same as above. With default SHT_DEFAULT_ADDRESS.
|
||
- **bool read(bool fast = true)** blocks 4 (fast) or 15 (slow) milliseconds + actual read + math.
|
||
Does read both the temperature and humidity.
|
||
- **bool isConnected()** check sensor is reachable over I2C. Returns false if not connected.
|
||
- **uint16_t readStatus()** details see datasheet and **Status fields** below.
|
||
- **uint32_t lastRead()** in milliSeconds since start of program.
|
||
- **bool reset(bool hard = false)** resets the sensor, soft reset by default. Returns false if it fails.
|
||
- **float getHumidity()** computes the relative humidity in % based on the latest raw reading, and returns it.
|
||
- **float getTemperature()** computes the temperature in <20>C based on the latest raw reading, and returns it.
|
||
- **float getFahrenheit()** computes the temperature in <20>F based on the latest raw reading, and returns it.
|
||
- **uint16_t getRawHumidity()** returns the raw two-byte representation of humidity directly from the sensor.
|
||
- **uint16_t getRawTemperature()** returns the raw two-byte representation of temperature directly from the sensor.
|
||
|
||
Note that the temperature and humidity values are recalculated on every call to **getHumidity()** and **getTemperature()**.
|
||
If you're worried about the extra cycles, you should make sure to cache these values or only request them after
|
||
you've performed a new reading.
|
||
|
||
|
||
#### Error interface
|
||
|
||
- **int getError()** returns last set error flag and clear it.
|
||
Be sure to clear the error flag by calling **getError()** before calling
|
||
any command as the error flag could be from a previous command.
|
||
|
||
| Error | Symbolic | Description |
|
||
|:-------:|:----------------------------|:------------------------------|
|
||
| 0x00 | SHT31_OK | no error |
|
||
| 0x81 | SHT31_ERR_WRITECMD | I2C write failed |
|
||
| 0x82 | SHT31_ERR_READBYTES | I2C read failed |
|
||
| 0x83 | SHT31_ERR_HEATER_OFF | Could not switch off heater |
|
||
| 0x84 | SHT31_ERR_NOT_CONNECT | Could not connect |
|
||
| 0x85 | SHT31_ERR_CRC_TEMP | CRC error in temperature |
|
||
| 0x86 | SHT31_ERR_CRC_HUM | CRC error in humidity |
|
||
| 0x87 | SHT31_ERR_CRC_STATUS | CRC error in status field |
|
||
| 0x88 | SHT31_ERR_HEATER_COOLDOWN | Heater need to cool down |
|
||
| 0x88 | SHT31_ERR_HEATER_ON | Could not switch on heater |
|
||
|
||
|
||
#### Heater interface
|
||
|
||
**WARNING:** Do not use heater for long periods.
|
||
|
||
Use the heater for max **180** seconds, and let it cool down **180** seconds = 3 minutes.
|
||
SHT31 version 0.3.3 and up guards the cool down time by preventing switching the heater on
|
||
within **180** seconds of the last switch off. Note: this guarding is not reboot persistent.
|
||
|
||
**WARNING:** The user is responsible to switch the heater off manually!
|
||
|
||
The class does **NOT** do this automatically.
|
||
Switch off the heater by directly calling **heatOff()** or indirectly by calling **isHeaterOn()**.
|
||
|
||
- **void setHeatTimeout(uint8_t seconds)** Set the time out of the heat cycle.
|
||
This value is truncated to max 180 seconds.
|
||
- **uint8_t getHeatTimeout
|
||
- **bool heatOn()** switches heat cycle on if not already on.
|
||
Returns false if fails, setting error to **SHT31_ERR_HEATER_COOLDOWN**
|
||
or to **SHT31_ERR_HEATER_ON**.
|
||
- **bool heatOff()** switches heat cycle off.
|
||
Returns false if fails, setting error to **SHT31_ERR_HEATER_OFF**.
|
||
- **bool isHeaterOn()** is the sensor still in heating cycle? replaces **heatUp()**.
|
||
Will switch the heater off if max heating time has passed.
|
||
- **bool heatUp()** will be obsolete in the future. replaced by **isHeaterOn()**
|
||
|
||
|
||
#### Async interface
|
||
|
||
See async example for usage
|
||
|
||
- **bool requestData()** requests a new measurement. Returns false if this fails.
|
||
- **bool dataReady()** checks if enough time has passed to read the data. (15 milliseconds)
|
||
- **bool readData(bool fast = true)** fast = true skips the CRC check.
|
||
Returns false if reading fails or in case of a CRC failure.
|
||
|
||
|
||
## Status fields
|
||
|
||
| BIT | Description | value | notes |
|
||
|:------|:-----------------------------|:--------|:--------|
|
||
| 15 | Alert pending status | 0 | no pending alerts
|
||
| | | 1 | at least one pending alert - default
|
||
| 14 | Reserved | 0 |
|
||
| 13 | Heater status | 0 | Heater OFF - default
|
||
| | | 1 | Heater ON
|
||
| 12 | Reserved | 0 |
|
||
| 11 | Humidity tracking alert | 0 | no alert - default
|
||
| | | 1 | alert
|
||
| 10 | Temperature tracking alert | 0 | no alert - default
|
||
| | | 1 | alert
|
||
| 9-5 | Reserved | 00000 |
|
||
| 4 | System reset detected | 0 | no reset since last <20>clear status register<65> command
|
||
| | | 1 | reset detected (hard or soft reset command or supply fail) - default
|
||
| 3-2 | Reserved | 00 |
|
||
| 1 | Command status | 0 | last command executed successfully
|
||
| | | 1 | last command not processed. Invalid or failed checksum
|
||
| 0 | Write data checksum status | 0 | checksum of last write correct
|
||
| | | 1 | checksum of last write transfer failed
|
||
|
||
|
||
## Future
|
||
|
||
#### Must
|
||
|
||
- keep in sync with (leading) SHT31 and SHT31_SW library.
|
||
|
||
#### Should
|
||
|
||
#### Could
|
||
|
||
#### Wont
|
||
|
||
|
||
## Support
|
||
|
||
If you appreciate my libraries, you can support the development and maintenance.
|
||
Improve the quality of the libraries by providing issues and Pull Requests, or
|
||
donate through PayPal or GitHub sponsors.
|
||
|
||
Thank you,
|
||
|