SBOA631 August   2025 HDC1010 , HDC1080 , HDC2010 , HDC2021 , HDC2022 , HDC2080 , HDC3020 , HDC3020-Q1 , HDC3021 , HDC3021-Q1 , HDC3022 , HDC3022-Q1 , HDC3120 , HDC3120-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Digital I2C Interface Overview
    1. 2.1 Register Map Protocol
      1. 2.1.1 A Quick Overview of I2C Register Map Protocol
        1. 2.1.1.1 HDC1x
        2. 2.1.1.2 HDC2x
          1. 2.1.1.2.1 Interfacing in Trigger-On Demand Mode
          2. 2.1.1.2.2 Interfacing Using Auto Measurement Mode (AMM)
    2. 2.2 Command Protocol
      1. 2.2.1 HDC302x
        1. 2.2.1.1 Interfacing in Trigger-On Demand Mode (One-Shot)
        2. 2.2.1.2 Interfacing in Auto Measurement Mode (AMM)
        3.       How to Check Measurement Data With CRC
  6. 3Analog Interface Overview
    1. 3.1 HDC3120
  7. 4Summary
  8. 5Development Support and Documentation
    1. 5.1 Software Support
    2. 5.2 References

2.2.1 HDC302x

The HDC302x family introduces a command-based interface, marking a departure from the register map-based scheme used in prior generations. Instead of writing to specific registers, HDC302x devices respond to well-defined command codes to initiate measurements, configure settings, or retrieve data. Table 2-6 shows an example of supported commands by the HDC302x devices.

This approach simplifies the interface and reduces the number of required I2C transactions, particularly in applications where only basic measurements are needed.

The forthcoming sections demonstrate how to interface with the HDC302x in both Trigger-On Demand and Auto Measurement modes, providing examples of how command-based communication is implemented in each case.

Table 2-6 HDC302x Command Table Snippet
HEX CODE
(MSB)		 HEX CODE
(LSB)		 COMMAND COMMAND DETAIL
24 00 Trigger-On Demand Mode
Single Temperature (T) Measurement
and Relative Humidity (RH) Measurement		 Low Power Mode 0 (lowest noise)
24 0B Low Power Mode 1
24 16 Low Power Mode 2
24 FF Low Power Mode 3 (lowest power)
20 32 Auto Measurement Mode
1 measurement per 2 seconds.		 Low Power Mode 0 (lowest noise)
20 24 Low Power Mode 1
20 2F Low Power Mode 2
20 FF Low Power Mode 3 (lowest power)
21 30 Auto Measurement Mode
1 measurement per second.		 Low Power Mode 0 (lowest noise)
21 26 Low Power Mode 1
21 2D Low Power Mode 2
21 FF Low Power Mode 3 (lowest power)
22 36 Auto Measurement Mode
2 measurements per second.		 Low Power Mode 0 (lowest noise)
22 20 Low Power Mode 1
22 2B Low Power Mode 2
22 FF Low Power Mode 3 (lowest power)
23 34 Auto Measurement Mode
4 measurements per second.		 Low Power Mode 0 (lowest noise)
23 22 Low Power Mode 1
23 29 Low Power Mode 2
23 FF Low Power Mode 3 (lowest power)
27 37 Auto Measurement Mode
10 measurements per second.		 Low Power Mode 0 (lowest noise)
27 21 Low Power Mode 1
27 2A Low Power Mode 2
27 FF Low Power Mode 3 (lowest power)
2C 06 Trigger-On Demand Mode
Single Temperature (T) Measurement
and Relative Humidity (RH) Measurement		 Low Power Mode 0 (lowest noise)
2C 0D Low Power Mode 1
2C 10 Low Power Mode 2
30 93 Auto Measurement Mode Exit, then return to Trigger-on Demand Mode.
E0 00 Measurement Readout of T and RH

(Note: if RH and T are not updated, data read outs all FFs)

E0

01

Measurement Readout of RH only
E0 02 Measurement History Readout of Minimum T.
E0 03 Measurement History Readout of Maximum T.
E0 04 Measurement History Readout of Minimum RH.
E0 05 Measurement History Readout of Maximum RH.