mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
4.6 KiB
4.6 KiB
SHT31
Arduino library for the SHT31 temperature and humidity sensor
Description
The SHT3x family of sensors should work up to 1 MHz I2C
This library should also work for SHT30 and SHT35 but these are not tested yet.
| SENSOR | Temperature accuracy | Humidity accuracy |
|---|---|---|
| SHT30 | ~0.3 | 2 |
| SHT31 | ~0.3 | 1.5 |
| SHT35 | ~0.2 | 1.5 |
An elaborated library for the SHT31 sensor can be found here https://github.com/hawesg/SHT31D_Particle_Photon_ClosedCube
Interface
Base interface
- SHT31() constructor.
- begin(address, dataPin, clockPin) begin function for ESP8266 & ESP32; returns false if device address is incorrect or device cannot be reset.
- begin(address) for single I2C bus platforms, e.g UNO.
- begin(address, TwoWire *wire) for platforms with multiple I2C busses.
- read(bool fast = true) blocks 4 (fast) or 15 (slow) milliseconds + actual read + math
- 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.
- reset(bool hard = false) resets the sensor, soft reset by default. Returns false if fails.
- getHumidity() returns relative humidity in %
- getTemperature() returns temperature in °C
Error interface
- 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 statusfield |
Heater interface
Use the heater for max 180 seconds, and let it cool down an equal period of time.
WARNING: Do not use heater for long periods.
WARNING: The user is responsible to switch the heater off manually! The class does NOT do this automatically.
- setHeatTimeout(uint8_t seconds) Set the time out of the heat cycle. This value is truncated to max 180 seconds.
- heatOn() switches heat cycle on. Returns false if fails.
- heatOff() switches heat cycle off. Returns false if fails.
- isHeaterOn() is the sensor still in heating cycle? replaces heatUp(). Will switch heat off if max heating time has passed.
- heatUp() will be obsolete in the future.
Async interface
See async example for usage
- requestData() requests a new measurement. Returns false if this fails.
- dataReady() checks if enough time has passed to read the data. (15 millis)
- readData(bool fast = true) fast skips CRC check. Returns false if reading fails or in case of a CRC fail.
Status fields
| BIT | Description | values |
|---|---|---|
| 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 ‘clear status register’ command |
| '1': reset detected (hard or soft reset command or supply fail) - default | ||
| 3-2 | Reserved | '00' |
| 1 | Command status | '0': last cmd executed successfully |
| '1': last cmd not processed. Invalid or failed checksum | ||
| 0 | Write data checksum status | '0': checksum of last write correct |
| '1': checksum of last write transfer failed |
Operation
See examples