Beginner
10 min

Get in sync with mother nature uaing DHT22 and PIC18F57Q43

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DHT22 Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

DHT22 Click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Our temperature and humidity sensing solution delivers the data you need for informed decision-making, risk assessment, and proactive maintenance, enabling you to take timely actions and ensure optimal conditions in any setting

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Hardware Overview

How does it work?

DHT22 Click is based on the DHT22, a digital humidity sensor with an integrated temperature sensor and a calibrated output signal from Aosong Electronics. The DHT22 utilizes an exclusive digital-signal-collecting technique and humidity sensing technology, assuring its reliability and stability. It can read humidity over the full range of 0 to 100% RH with a typical accuracy of ±2-5%, while its maximum temperature range is from -40 to 80°C with a typical accuracy of ±0.5°C. As mentioned, the DHT22 uses a capacitive humidity sensor and

a thermistor to measure the surrounding air, providing a digital signal for the host controller on one of the two possible mikroBUS™ pins, CS and Int pins of the mikroBUS™ socket marked as SD1 and SD2. An onboard SMD jumper labeled as SDA SEL can select the desirable processing line, placing it in an appropriate position marked as SDA1 or SDA2. This Click board™ only requires careful timing to grab the data. The DHT22 can only get new data once every two seconds, meaning the sensor readings can be up to two

seconds old. This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the PWR SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to 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.

DHT22 Click hardware overview image

Features overview

Development board

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

48

RAM (Bytes)

8196

You complete me!

Accessories

Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.

Curiosity Nano Base for Click boards accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
Data Signal
PD4
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Data Signal
PA6
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

DHT22 Click Schematic schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Curiosity Nano Base for Click boards front image hardware assembly
Barometer 13 Click front image hardware assembly
PIC18F57Q43 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Curiosity Nano with PICXXX 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 image step 5 hardware assembly
Necto image step 6 hardware assembly
PIC18F57Q43 Curiosity MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for DHT22 Click driver.

Key functions:

  • dht22_start_signal - Sends start signal to the sensor function

  • dht22_check_sensor_response - Release the bus to wait the sensor response signal function

  • dht22_get_sensor_data - Reading data from the sensor function

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * \file 
 * \brief DHT22 Click example
 *
 * # 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.
 *
 * ## Application Task
 * Reads the temperature and humidity from the sensor and 
 * displays the values on the USB UART.
 *
 * \author Nemanja Medakovic
 *
 */

#include "board.h"
#include "log.h"
#include "dht22.h"

static dht22_t dht22;
static log_t logger;

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. ----" );
}

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 );
                }
                
            }
        }
    }
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}

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

Additional Support

Resources

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