GY-63_MS5611/libraries/SHT31

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