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Temp&Hum 13 Click with Fusion for STM32 v8

Published Nov 08, 2023

Click board™

Temp&Hum 13 Click

Development board

Fusion for STM32 v8


NECTO Studio



Take control of your surroundings and make data-driven decisions for maximum comfort and productivity.



Hardware Overview

How does it work?

Temp&Hum 13 Click is based on the HTU21DF, a digital relative humidity sensor with temperature output from TE Connectivity. This sensor is factory calibrated to ±2% relative humidity and ±0.3°C temperature accuracy. It has an integrated heating element that is used for functionality diagnosis as well. This heating element can be simply activated by setting a bit in the appropriate register. In the case when the heater is powered on, the typical power consumption is about 5.5mW. Internally, two sensors are connected to the two separated ADC sections with variable resolution of 12 -14 bits for the temperature and 8-12 bits for relative humiditiy measurement. The OTP memory holds the calibration coefficients that are applied to the measured value and the results are stored on the output registers, in the MSB/LSB format. These values are then used in formulas found in the HTU21DF datasheet so that the final temperature or relative humidity data can be

calculated. It is also possible to correct the offsets with custom values. Temp&Hum 13 click uses the I2C protocol to communicate with the host MCU. Its I2C bus pins are routed to the mikroBUS™ I2C pins and are pulled to a HIGH logic level by the onboard resistors. The final I2C address of this IC is factory determined. There are two different operation modes to communicate with the HTU21D sensor: Hold Master mode and No Hold Master mode. In the first case, the SCK line is blocked (controlled by HTU21D(F) sensor) during measurement process while in the second case the SCK line remain open for other communication while the sensor is processing the measurement. The HTU21DF IC itself is a very low power consumption device and it can work in two modes: sleep and active (measurement) mode. The device enters the sleep the mode as soon as possible, to save power. This makes the HTU21DF suitable to be used in battery-powered applications. In these

applications, the HTU21DF spends most of the time in sleep mode, with the typical current consumption of 20 nA. While in the active mode, the typical current consumption is 450µA. The provided Click board™ library contains simple and easy to use functions, which simplify configuring and reading of the measurement data. These functions are demonstrated in the included example application and can be used as a reference for custom projects. These functions can be used in mikroC, mikroBasic and mikroPascal compilers for all MCU architectures, supported by MikroElektronika. This Click Board™ is designed to be operated only with 3.3V logic level. A proper logic voltage level conversion should be performed before the Click board™ is used with MCUs with logic levels of 5V. It is ready to be used as soon as it is inserted into a mikroBUS™ socket of the development system.

Temp&Hum 13 Click hardware overview image

Features overview

Development board

Fusion for STM32 v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different 32-bit ARM® Cortex®-M based MCUs from STMicroelectronics, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, Fusion for STM32 v8 provides a fluid and immersive working experience, allowing

access anywhere and under any circumstances at any time. Each part of the Fusion for STM32 v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. Fusion for STM32 v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Fusion for STM32 v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Power Supply
I2C Clock
I2C Data

Take a closer look


Temp&Hum 13 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Fusion for STM32 v8 as your development board.

Fusion for PIC v8 front image hardware assembly
Buck 22 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
v8 SiBRAIN MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Temp&Hum 13 Click driver.

Key functions:

  • temphum13_get_humidity - This function calculates humidity.

  • temphum13_get_temperature -This function calculates current temperature.

  • temphum13_change_resolution - This function sets click measurement resolution.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * \file 
 * \brief TempHum13 Click example
 * # Description
 * This demo shows basic TempHum13 click functionality - temperature
 * and humidity measurement. 
 * The demo application is composed of two sections :
 * ## Application Init 
 * Initialize device.
 * ## Application Task  
 * Measure temperature and humidity values on every 0,5 seconds,
 * and log them to UART Terminal if they are valid.
 * \author MikroE Team
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "temphum13.h"

// ------------------------------------------------------------------ VARIABLES

static temphum13_t temphum13;
static log_t logger;

static float temperature;
static float humidity;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
    log_cfg_t log_cfg;
    temphum13_cfg_t cfg;

     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, "---- Application Init ----" );

    //  Click initialization.

    temphum13_cfg_setup( &cfg );
    temphum13_init( &temphum13, &cfg );
    temphum13_default_cfg( &temphum13 );

void application_task ( void )
    temperature = temphum13_get_temperature( &temphum13 );
    humidity = temphum13_get_humidity( &temphum13 );
    if ( temperature != 65536.0 )
        log_printf( &logger, "\r\n> Temperature : %.2f C", temperature );

    if ( humidity != 65536.0 )
        log_printf( &logger, "\r\n> Humidity    : %.2f%%RH\r\n", humidity );

    Delay_ms( 500 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

// ------------------------------------------------------------------------ END

Additional Support