This set of commands will trigger a single measurement acquisition of temperature, followed by relative humidity. The HDC302x will transition from sleep mode into measurement mode, and upon measurement completion, return to sleep mode. There are four possible Trigger On Demand commands, each one corresponding to a different low power mode (and therefore, different levels of power consumption). Table 8-3 shows these commands.
The measurement readout from these commands is obtained through an I2C read sequence, as previously documented in Section 8.5.4 and Section 8.5.5. The format of the measurement readout is two bytes of data representing temperature, followed by one byte CRC checksum, and then another two bytes of data representing relative humidity, followed by one byte CRC checksum as illustrated in Figure 8-15.
If the I2C controller attempts to read the measurements results prior to measurement completion, the HDC302x will respond with a NACK condition, as illustrated in Figure 8-16.