This section outlines how to configure the HDC302x for AMM and explains the key differences compared to Trigger-On Demand mode.

The main distinction between Auto Measurement Mode and Trigger-On Demand is if users intend to read from the HDC302x sensor in a fixed interval, Auto Measurement Mode would be more suitable for its programmable output interval. Figure 2-8 illustrates the command sequence for programming an HDC302x to output a single measurement every second with the lowest noise and highest repeatability.

Figure 2-8 HDC302x Auto Measurement Mode (AMM) Communication Structure

// configure HDC302x for Auto Measurement Mode (1 measurement/sec)
// lowest noise, highest repeatability 
void deviceInit() {

    Wire.beginTransmission(0x44);
    Wire.write(0x21); //send MSB of command
    Wire.write(0x30); //command LSB
    Wire.endTransmission();
    delay(15); //wait 15ms before reading

}

After the device is configured for Auto Measurement Mode, and sufficient time has passed for a conversion to complete (one second in this case), the following function is used to request the stored measurement data:

// Helper function for requesting data when in Auto Measurement Mode
void requestData() {

    Wire.beginTransmission(DEVICE_ADDR); // initiate communication
    Wire.write(0xE0); // send MSB of read command
    Wire.write(0x00); // send LSB of read command
    Wire.endTransmission();

}

To continuously poll the device in AMM, you can issue the read command to retrieve the latest measurement data at the configured sampling rate (measurements per second).

A complete Arduino example demonstrating HDC302x operation in AMM – including device configuration, measurement polling, and data readout is available in the TI GitHub? repository for environmental sensors here.