SHT3x - Temp/Humd sensor
SHT3x - Temperature and humidity sensor
Temperature/humidity sensor using I2C bus.
Process flow
1 Wire.begin()
: Initialize bus 2 .setup()
: Initialize the sensor 3..begin()
: Start operation of the sensor 4. 4.wait(): wait for a few ms 5.
.available()becomes
true 6. .get_temp(), .get_humid()
: read values
Procedures required for operation
Wire bus
Before calling setup()
method, Wire is put into operation by Wire.begin()
.
Procedures when returning from sleep mode
Keep the Wire bus in the operating state just before sleep (the Wire is automatically restored after sleep).
Code Example
#include <TWELITE>
#include <SNS_SHT3X>
SNS_SHT3X sns_sht3x; // Declaration of Objects
#include <SNS_SHT3X>
and declaration of SNS_SHT3X
class object is required.
Initialization
void setup() {
Wire.begin();
sns_sht3x.setup();
}
Start acquiring sensor values
void loop() {
if(eState == E_STATE::INIT) {
sns_sht3x.begin();
eState = E_STATE::CAPTURE;
}
}
Call .begin()
to start acquiring sensor values. It takes several ms to complete.
In the above loop()
, the process is designed to branch according to the state variable "eState". (Reference)
Waiting for sensor value acquisition
void loop() {
if(eState == E_STATE::CAPTURE) {
if (sns_sht3x.available()) {
// Sensor value readout available
}
}
}
Whether the sensor value is ready or not can be determined by .available()
.
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() << '%';
}
}
}
As soon as the sensor value is ready, the value can be read out.
.get_temp(), get_humid()
includes floating point operations; you can also get 100x integer values.
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(" T=%c%d.%02d", humd.neg ? '-' : ' ', humd.quo, humd.rem);
Here div100()
is used to decompose 100x values into integer and decimal parts.
Methods
get_temp(), get_temp_cent()
double get_temp()
int16_t get_temp_cent()
Read temperature. get_temp()
returns a value in °C and get_temp_cent()
returns an integer value that is 100 times the value in °C.
On error, values between -32760 and -32768 are returned.
get_humid(), get_humid_per_dmil()
double get_humid()
int16_t get_humid_per_dmil()
Reads the humidity. get_humid()
returns a value in %, and get_humid_per_dmil()
returns an integer value of 100 times %.
On error, values between -32760
and -32768
are returned.
Common methods
setup()
void setup(uint32_t arg1 = 0UL)
Allocates and initializes the memory area for the sensor.
The 8 bits from LSB of arg1
can store the I2C address. If not specified, leave it as 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 furthre I2C comm.
sns_sht3x.setup(0x45); // alternative ID
if (sns_sht3x.probe()) b_found_sht3x = true;
} else {
b_found_sht3x = true;
}
}
In the above example, we first try to initialize with the default I2C ID, and if there is no response, we try to initialize with an address of 0x45
.
begin(), end()
void begin()
void end()
Starts acquiring a sensor. It takes a few ms to read the value of the sensor and must wait until available()
is true
.
It does not support end()
.
process_ev()
void process_ev(uint32_t arg1, uint32_t arg2 = 0)
In the case of a sensor with wait processing, arg1
is given E_EVENT_TICK_TIMER
or E_EVENT_START_UP
to indicate the elapse of time. After calling this method, if the required time has elapsed, available()
will be set to true
and the sensor value can be read.
available()
bool available()
Returns true
when the sensor satisfies the readout condition.
probe()
bool probe()
Returns true
when the sensor is connected.
sns_stat()
uint32_t sns_stat()
Various information of the sensor device is stored.
Stored values are undefined for this device.
sns_opt()
uint32_t& sns_opt()
The value passed in setup(uint32_t arg1)
is stored.
The lower 8 bits contain the address of the specified I2C device.
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