dht22

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DHT22 click

DHT22 click is a temperature and humidity measurement board carrying the sensor of the same name.

click Product page

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Click library

• Author : MikroE Team
• Date : May 2020.
• Type : GPIO type

Software Support

We provide a library for the Dht22 Click as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Package can be downloaded/installed directly form compilers IDE(recommended way), or downloaded from our LibStock, or found on mikroE github account.

Library Description

This library contains API for Dht22 Click driver.

Standard key functions :

• Config Object Initialization function.

void dht22_cfg_setup ( dht22_cfg_t *cfg );

• Initialization function.

DHT22_RETVAL dht22_init ( dht22_t *ctx, dht22_cfg_t *cfg );

Example key functions :

• Sends start signal to the sensor function.

void dht22_start_signal ( dht22_t *ctx );

• Release the bus to wait the sensor response signal function.

uint8_t dht22_check_sensor_response ( dht22_t *ctx );

• Reading data from the sensor function.

uint32_t dht22_get_sensor_data ( dht22_t *ctx );

Examples Description

This is a example which demonstrates the use of DHT22 Click board by measuring temperature and relative humidity.

The demo application is composed of two sections :

Application Init

Initializes the SDA data pin depending on the selected GPIO pin (SDA1/SDA2) and log module.

void application_init ( void )
{
    log_cfg_t log_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... ----" );

    dht22_cfg_t dht22_cfg;

    //  Click initialization.

    dht22_cfg_setup( &dht22_cfg );
    DHT22_MAP_MIKROBUS( dht22_cfg, MIKROBUS_1 );

    if ( dht22_init( &dht22, &dht22_cfg ) == DHT22_ERROR )
    {
        log_info( &logger, "---- Application Init Error. ----" );
        log_info( &logger, "---- Please, run program again... ----" );

        for ( ; ; );
    }

    log_info( &logger, "---- Application Init done. ----" );
}
  

Application Task

Reads the temperature and humidity from the sensor and displays the values on the USB UART.

void application_task ( void )
{
    uint8_t resp_stat = DHT22_RESP_NOT_READY;
    uint32_t sens_meas = 0;
    float dht22_temp = 0;
    float dht22_hum = 0;
    
    dht22_init_sda_output( &dht22 );
    
    if ( dht22_start_signal( &dht22 ) == DHT22_OK )
    {
        dht22_init_sda_input( &dht22 );
        
        if ( dht22_check_sensor_response( &dht22, &resp_stat ) == DHT22_OK )
        {
            if ( resp_stat == DHT22_RESP_READY )
            {
                if ( dht22_get_sensor_data( &dht22, &sens_meas ) == DHT22_OK )
                {
                    dht22_temp = dht22_calculate_temperature( &dht22, sens_meas );
                    dht22_hum = dht22_calculate_humidity( &dht22, sens_meas );

                    log_printf( &logger, " Humidity : %.2f %%\r\n", dht22_hum );
                    log_printf( &logger, " Temperature : %.2f degC\r\n", dht22_temp );
                    log_printf( &logger, " ---------------------------\r\n", dht22_temp );
                    Delay_ms( 1000 );
                }
                
            }
        }
    }
}  

The full application code, and ready to use projects can be installed directly form compilers IDE(recommneded) or found on LibStock page or mikroE GitHub accaunt.

Other mikroE Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Dht22

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all Mikroelektronika compilers, or any other terminal application of your choice, can be used to read the message.

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