SHT3x

Processing Flow

1. Wire.begin(): Initialize the bus
2. .setup(): Initialize the sensor
3. .begin(): Start the sensor
4. Wait for a few milliseconds
5. .available() becomes true
6. .get_temp(), .get_humid(): Read values

Required Procedures for Operation

Wire Bus

Before calling the setup() method, initialize the Wire with Wire.begin().

Procedure After Waking from Sleep

Ensure the Wire bus is active just before entering sleep (Wire will be automatically recovered after waking).

Code Example

##include <TWELITE>
##include <SNS_SHT3X>

SNS_SHT3X sns_sht3x; // Declare the object

Include #include <SNS_SHT3X> and declare an object of the SNS_SHT3X class.

Initialization

void setup() {
    Wire.begin();
    sns_sht3x.setup();
}

Starting Sensor Reading

void loop() {

  if(eState == E_STATE::INIT) {
    sns_sht3x.begin();
    eState = E_STATE::CAPTURE;
  }

}

To begin reading sensor values, call .begin(). It takes a few milliseconds to complete.

※ The above loop() assumes a state-machine design using the eState variable. (Reference)

Waiting for Sensor Reading

void loop() {

  if(eState == E_STATE::CAPTURE) {
    if (sns_sht3x.available()) {
      // Sensor values are ready
    }
  }

}

Check .available() to determine whether the sensor values are ready.

Reading Sensor Values

void loop() {

  if(eState == E_STATE::CAPTURE) {
    if (sns_sht3x.available()) {
      Serial << crlf << "SHT3X:"
            << " T=" << sns_sht3x.get_temp() << 'C'
            << " H=" << sns_sht3x.get_humid() << '%';
    }
  }

}

Once the sensor values are ready, you can read them.

.get_temp() and .get_humid() use floating point operations. You can also retrieve values as integers scaled by 100.

auto temp = div100(sns_sht3x.get_temp_cent());
auto humd = div100(sns_sht3x.get_humid_per_dmil);

Serial << crlf << "SHT3X:"
  << format(" T=%c%d.%02d", temp.neg ? '-' : ' ', temp.quo, temp.rem)
  << format(" H=%c%d.%02d", humd.neg ? '-' : ' ', humd.quo, humd.rem);

In this example, div100() is used to split the x100 values into integer and fractional parts.

Methods

get_temp(), get_temp_cent()

double get_temp()
int16_t get_temp_cent()

Reads the temperature. get_temp() returns °C, while get_temp_cent() returns the value scaled by 100 as an integer.

On error, it returns a value between -32760 and -32768.

get_humid(), get_humid_per_dmil()

double get_humid()
int16_t get_humid_per_dmil()

Reads the humidity. get_humid() returns %RH, while get_humid_per_dmil() returns the value scaled by 100 as an integer.

On error, it returns a value between -32760 and -32768.

Common Methods

setup()

void setup(uint32_t arg1 = 0UL)

Allocates memory and initializes the sensor.

You can specify the I2C address in the lower 8 bits of arg1. If unspecified, it defaults to 0.

##include <SNS_SHT3X>
SNS_SHT3X sns_sht3x;
bool b_found_sht3x = false;

void setup() {
    sns_sht3x.setup();
    if (!sns_sht3x.probe()) {
        delayMicroseconds(100); // just in case, wait for devices to listen further I2C comm.
        sns_sht3x.setup(0x45); // alternative ID
        if (sns_sht3x.probe()) b_found_sht3x = true;
    } else {
        b_found_sht3x = true;
    }
}

In this example, it first tries to initialize with the default I2C ID. If no response, it retries with address 0x45.

begin(), end()

void begin()
void end()

Begins sensor reading. It takes a few milliseconds before values become ready, during which .available() returns false.

end() is not supported.

process_ev()

void process_ev(uint32_t arg1, uint32_t arg2 = 0)

For sensors that require waiting, provide E_EVENT_TICK_TIMER or E_EVENT_START_UP in arg1 to notify the passage of time. If enough time has elapsed after calling this method, .available() will return true and the sensor value can be read.

available()

bool available()

Returns true when the sensor is ready to be read.

probe()

bool probe()

Returns true if the sensor is connected.

sns_stat()

uint32_t sns_stat()

Stores various information about the sensor device.

• The stored value is undefined for this device.

sns_opt()

uint32_t& sns_opt()

Returns the value passed to setup(uint32_t arg1).

• The lower 8 bits store the specified I2C device address.