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Temp&Hum 21 Click with Fusion for ARM v8

Published Apr 04, 2023

Click board™

Temp&Hum 21 Click

Development board

Fusion for ARM v8


NECTO Studio



In case the online weather forecast is not that accurate



Hardware Overview

How does it work?

Temp&Hum 21 Click is based on the HIH8130-021-001, a highly accurate, fully-calibrated digital humidity and temperature sensor from Honeywell Sensing and Productivity Solutions. The humidity can be measured within a range of 0 to 100%RH, while the temperature sensor is designed for a range of -40 to +120°C. The typical accuracy for humidity is ±2%RH in the measuring range of 10 up to 90%RH at ambient temperature and ±0.5°C for its operating temperature range with low power consumption. The HIH8130-021-001 communicates with MCU using the standard I2C 2-Wire interface to read and write data supporting

Fast Mode operation with a clock frequency up to 400kHz, providing factory-calibrated 14-bit data to the host controller. High 14-bit humidity and 14-bit temperature sensor resolution within the application help the user’s design detect the slightest relative humidity or temperature change. It also has an alarm feature with configurable alarm thresholds routed to the ALH and ALL pins of the mikroBUS™ socket for preset control at a minimum and maximum humidity and temperature. These alarm thresholds are set to generate alarms when the actual values in the devices cross the defined threshold values.

To activate the external setting of the alarm thresholds, it is necessary to populate resistors R4 and R5, which are not populated by default, to enable an external setting on an unpopulated header in the middle of the Click board™. This 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.

Temp&Hum 21 Click top side image
Temp&Hum 21 Click lateral side image
Temp&Hum 21 Click bottom side image

Features overview

Development board

Fusion for ARM 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 ARM® Cortex®-M based MCUs 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 ARM v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the Fusion for ARM 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 ARM 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 ARM 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

Alarm Low Threshold
Power Supply
Alarm High Threshold
I2C Clock
I2C Data
Power Supply

Take a closer look


Temp&Hum 21 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 ARM 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 TempHum 21 Click driver.

Key functions:

  • temphum21_read_measurementThis function requests measurement and waits for a measurement to complete and, after that, reads the temperature in Celsius and relative humidity in percents.

  • temphum21_get_all_pin This function returns the alarm low (ALL) pin logic state.

  • temphum21_get_alh_pin This function returns the alarm high (ALH) pin logic state.

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 main.c
 * @brief TempHum21 Click example
 * # Description
 * This example demonstrates the use of Temp & Hum 21 click board by reading
 * the temperature and humidity data.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes the driver and logger.
 * ## Application Task
 * Reads the temperature (Celsius) and humidity (Percents) data and displays the
 * results on the USB UART approximately once per second.
 * @author Stefan Filipovic

#include "board.h"
#include "log.h"
#include "temphum21.h"

static temphum21_t temphum21;
static log_t logger;

void application_init ( void ) 
    log_cfg_t log_cfg;  /**< Logger config object. */
    temphum21_cfg_t temphum21_cfg;  /**< Click config object. */

     * 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.
    temphum21_cfg_setup( &temphum21_cfg );
    TEMPHUM21_MAP_MIKROBUS( temphum21_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == temphum21_init( &temphum21, &temphum21_cfg ) ) 
        log_error( &logger, " Communication init." );
        for ( ; ; );
    log_info( &logger, " Application Task " );

void application_task ( void ) 
    float temperature, humidity;
    if ( TEMPHUM21_STATUS_NORMAL_OP == temphum21_read_measurement ( &temphum21, &temperature, &humidity ) )
        log_printf ( &logger, " Temperature: %.2f C\r\n", temperature );
        log_printf ( &logger, " Humidity: %.2f %%\r\n\n", humidity );
        Delay_ms ( 1000 );

void main ( void ) 
    application_init( );

    for ( ; ; ) 
        application_task( );

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

Additional Support