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#include<Wire.h>
// SI7005 I2C address is 0x40(64)
#define Addr 0x40
void setup()
{
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Serial.begin(9600);
delay(300);
}
void loop()
{
unsigned int data[3];
// Start I2C transmission
Wire.beginTransmission(Addr);
// Select configuration register
Wire.write(0x03);
// Command for temperature measurement
Wire.write(0x11);
// Stop I2C transmission
Wire.endTransmission();
delay(500);
// Start I2C transmission
Wire.beginTransmission(Addr);
// Select data register
Wire.write(0x00);
// Stop I2C transmission
Wire.endTransmission();
// Request 3 byte of data
Wire.requestFrom(Addr, 3);
// Read 3 byte of data
// status, temp_msb, temp_lsb
if (Wire.available() == 3)
{
data[0] = Wire.read();
data[1] = Wire.read();
data[2] = Wire.read();
}
// Keep checking for valid data
while ((data[0] & 0x01) != 0)
{
// Start I2C transmission
Wire.beginTransmission(Addr);
// Select data register
Wire.write(0x00);
// Stop I2C transmission
Wire.endTransmission();
// Request 3 byte of data
Wire.requestFrom(Addr, 3);
// Read 3 byte of data
// status, temp_msb, temp_lsb
if (Wire.available() == 3)
{
data[0] = Wire.read();
data[1] = Wire.read();
data[2] = Wire.read();
}
}
// Convert the data to 14-bits
int temp = ((data[1] * 256) + (data[2] & 0xFC)) / 4;
float cTemp = (temp / 32.0) - 50.0;
float fTemp = cTemp * 1.8 + 32;
// Start I2C transmission
Wire.beginTransmission(Addr);
// Select configuration register
Wire.write(0x03);
// Command for humidity measurement
Wire.write(0x01);
// Stop I2C transmission
Wire.endTransmission();
delay(300);
// Start I2C transmission
Wire.beginTransmission(Addr);
// Select data register
Wire.write(0x00);
// Stop I2C transmission
Wire.endTransmission();
// Request 3 byte of data
Wire.requestFrom(Addr, 3);
// Read 3 byte of data
// status, humidity_msb, humidity_lsb
if (Wire.available() == 3)
{
data[0] = Wire.read();
data[1] = Wire.read();
data[2] = Wire.read();
}
// Keep checking for valid data
while ((data[0] & 0x01) != 0)
{
// Start I2C transmission
Wire.beginTransmission(Addr);
// Select data register
Wire.write(0x00);
// Stop I2C transmission
Wire.endTransmission();
delay(300);
// Request 3 byte of data
Wire.requestFrom(Addr, 3);
// Read 3 byte of data
// status, humidity_msb, humidity_lsb
if (Wire.available() == 3)
{
data[0] = Wire.read();
data[1] = Wire.read();
data[2] = Wire.read();
}
}
// Convert the data to 12-bits
float humidity = ((data[1] * 256.0) + (data[2] & 0xF0)) / 16;
humidity = (humidity / 16.0) - 24.0;
// Output data to serial monitor
Serial.print("Relative humidity : ");
Serial.print(humidity);
Serial.println(" %RH");
Serial.print("Temperature in Celsius : ");
Serial.print(cTemp);
Serial.println(" C");
Serial.print("Temperature in Fahrenheit : ");
Serial.print(fTemp);
Serial.println(" F");
delay(500);
}