SLAA913A January   2020  – June 2021

 

  1.   Trademarks
  2. 1Introduction
  3. 2System Overview
    1. 2.1 Software
    2. 2.2 Hardware
  4. 3System Operation
    1. 3.1 HDC2010 Sensor Readout
    2. 3.2 I2C Protocol and Data Buffering for Low Power
  5. 4Test and Verification
    1. 4.1 EnergyTrace™ Results
    2. 4.2 Average Current Consumption
    3. 4.3 Power-Saving Effect of Data Buffering in RAM
  6. 5Summary
  7. 6References
  8. 7Revision History

2.2 Hardware

For the measurements, the following hardware (available at TI.com) was used:

HW modifications: the I2C-bus pullup resistors on the CC1352P LaunchPad were removed as these are in parallel to the I2C pullup resistors found on BOOSTXL-BASSENSORS. The pullup resistors on the BoosterPack™ plug-in module are wired to a CC1352P DIO pin (extra wire); the existing copper trace to the +3.3V pin of the CC1352P LaunchPad was cut on the PCB. In this power-optimized design, the new wiring allows for powering the I2C pullup resistors only when data is transferred.

As the ADDR pin of the HDC2010 device in BOOSTXL-BASSENSOR is connected to GND, its slave i2C address is 0x40 (see Figure 2-1). The 0x40 address becomes 0x80 (Write) or 0x81 (Read) when used in the Sensor Controller Studio, which inserts the read/write bit as the last bit after the 7-bit address, as Table 2-1 shows.

Table 2-1 HDC2010 I2C Slave Address
ADDR ADDRESS (7-BIT ADDRESS) BOOSTXL-BASSENSORS (8-BIT ADDRESS)
GND 1000000 0x80(W)/0x81(R)
VDD 1000001 0x82(W)/0x83(R)
Note:

The HDC_V+ pin uses active low level voltage to control the P-MOSFET which gates the power to the HDC2010 sensor.

GUID-9B2CBE9C-A6F5-4BA1-A109-D5D6EA90BE8B-low.png Figure 2-1 Interfacing to HDC2010, Power Supply Line is P-MOSFET Gated (Low Active)

After power up, the HDC2010 device can be configured to a sampling frequency from one sample every two minutes down to five samples every second. The raw values provided by the HDC2010 sensor have to be calculated or converted into a human readable format for temperature and humidity, see Equation 1 and Equation 2.

Equation 1. GUID-B8DD35F0-D733-4380-81D8-4515A6C1ACB9-low.gif
Equation 2. GUID-BB707305-56E5-46A5-BF38-8EED14B0369A-low.gif

Both of these equations are implemented in the Sensor Controller code example for demonstration purposes; however, the additional code reduces the available buffer memory for storing sensor data and negatively impacts the amount of data to be transmitted over-the-air.

For lowest power consumption, TI recommends to read and transmit the raw 16-bit humidity and 16-bit temperature sensor values over-the-air (after a packet with the desired payload length is created), while the conversion into a human readable format Equation 1 and Equation 2 can be done at the receiving or data display node.