Temp&Hum 24 Click Board™

How Does The Temp&Hum 24 Click Board™ Work?

The Temp&Hum 24 Click Board™ is based on the HDC3021. This integrated interface digital sensor incorporates both humidity and temperature sensing elements, an analogue-to-digital converter, calibration memory, and an I2C-compatible interface from Texas Instruments in one package. The sensor performs best when operated within the recommended average temperature and humidity range of 0-50°C and 10-50%RH, with each measurement in a 16-bit format. The HDC3021 also provides excellent measurement accuracy at low power (±0.5%RH and ±0.1°C over a wide operating temperature range).

The HDC3021 measures relative humidity through variations in the capacitance of a polymer dielectric. This sensor has a polyimide tape to cover the opening of the humidity sensor element, which protects it from pollutants that can be produced as part of the manufacturing process. The tape must be removed after the final stages of assembly to measure the relative humidity in the ambient environment accurately. To remove the polyimide tape from the humidity sensor element, TI recommends using an ESD-safe tweezer to grip the adhesive-free tab in the top right corner and slowly peel the adhesive from the top-right corner towards the bottom-left corner in an upward direction. This will help to reduce the risk of scratching the humidity sensor element.

Due to contaminants, the natural ageing of the sensor's polymer dielectric, and exposure to extreme operating conditions resulting in long-term drift, the HDC3021 accuracy can be offset. Thanks to the Offset Error Correction, the RH sensor offset reduces due to ageing, exposure to extreme operating conditions, and contaminants to return the sensor to within accuracy specifications.

This Click board™ communicates with an MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Fast Mode Plus up to 1MHz. The HDC3021 also has two measurement modes: Trigger-on Demand and Auto Measurement. Trigger-on Demand is a single temperature and relative humidity measurement reading triggered through an I2C command as needed. After the measurement is converted, the sensor remains in Sleep mode until another I2C command is received. Auto Measurement mode is a recurring temperature and relative humidity measurement reading, eliminating the need to repeatedly initiate a measurement request through an I2C command. The HDC3021 wakes from Sleep to measurement mode in this mode based on the selected sampling rate.

Besides, the HDC3021 allows choosing the least significant bit (LSB) of its I2C slave address using the SMD jumpers labelled ADDR SEL. It also possesses an additional interrupt alert signal, routed on the ALR pin of the mikroBUS™ socket, to provide a notification of ambient temperature and relative humidity measurements that violate programmed thresholds and general reset function routed on the RST pin of the mikroBUS™ socket.

The Temp&Hum 24 Click Board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout of the Temp&Hum 24 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

ONBOARD SETTINGS AND INDICATORS

TEMP&HUM 24 CLICK ELECTRICAL SPECIFICATIONS