Beginner
10 min

Maintain ideal temperature conditions with MAX31855K and PIC18F57Q43

Thermocouple-to-digital converter

THERMO Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

THERMO Click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Suitable for various scenarios, including thermostatic control, process monitoring, and other applications requiring accurate temperature data

A

A

Hardware Overview

How does it work?

THERMO Click is based on the MAX31855K, a sophisticated thermocouple-to-digital converter with a built-in 14-bit analog-to-digital converter (ADC) from Analog Devices. The thermocouple type is indicated in the suffix of the part number, which is why this Click board™ corresponds to the appropriate K-type thermocouple probe. The MAX31855K and PCC-SMP connector combination supports high-accuracy temperature measurement, which is ideal for thermostatic, process-control, and monitoring applications. The function of the thermocouple is to sense a difference in

temperature between two ends of the thermocouple wires. The thermocouple’s “hot” junction can be read across the operating temperature range, which for the MAX31855K is between -270 and 1372°C with a sensitivity of about 41μV/°C. It also features cold-junction compensation sensing and correction, a digital controller, and associated control logic. The reference junction, or “cold” end (which should be at the same temperature as the board on which the device is mounted), can range from -55°C to +125°C. While the temperature at the cold end fluctuates, the device accurately senses

the temperature difference at the opposite end. It provides temperature data to the host controller over an SPI interface (read-only). This Click board™ can only be operated with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

THERMO 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

The Type-K thermocouple, equipped with glass braid insulation, is a versatile tool designed for precision temperature measurements, particularly in high-temperature environments. With a calibrated Type-K configuration and a 24 AWG gage wire spanning 2 meters, this probe is engineered to provide reliable readings. Its operational temperature range extends to 480°C (900°F), making it suitable for demanding applications. The glass braid insulation ensures durability and stability during measurements, and the connector body can withstand temperatures up to 220°C (425°F). The Type-K thermocouple probe features a PCC-SMP connector at its end, which offers compatibility with THERMO Click and Thermo K Click boards. This connectivity makes it a valuable tool for various industrial and scientific settings, where precision and reliability in temperature monitoring are essential.

THERMO Click accessories image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
ID SEL
PA7
RST
SPI Select / ID COMM
PD4
CS
SPI Clock
PC6
SCK
SPI Data OUT
PC5
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

THERMO 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
Charger 27 Click front image hardware assembly
PIC18F47Q10 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Curiosity Nano with PICXXX Access 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 THERMO Click driver.

Key functions:

  • thermo_get_temperature - This function gets thermocouple temperature data

  • thermo_check_fault - This function checks fault states of MAX31855 sensor

  • thermo_read_data - This function reads the 32-bit of data from the sensor

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 Thermo Click example
 * 
 * # Description
 * This application collects data from the sensor, calculates it, and then logs
 * the results.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes driver and star write log.
 * 
 * ## Application Task  
 * Temperature measured by the thermocouple is converter by MAX31855 sensor 
 * and the results are logged. Displayed temperature is in degrees Celsius.
 * 
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "thermo.h"

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

static thermo_t thermo;
static log_t logger;

static float temperature;

// ------------------------------------------------------- ADDITIONAL FUNCTIONS

static void display_error_msg ( )
{
    log_printf( &logger, "       ERROR       \r\n" );

    if ( thermo_short_circuited_vcc( &thermo ) )
    {
        log_printf( &logger, "Short-circuted to Vcc\r\n" );
    }
    if ( thermo_short_circuited_gnd( &thermo ) )
    {
        log_printf( &logger, "Short-circuted to GND\r\n" );
    }
    if ( thermo_check_connections( &thermo ) )
    {
        log_printf( &logger, "No Connections\r\n" );
    }

}

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    thermo_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 ----" );

    thermo_cfg_setup( &cfg );
    THERMO_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    thermo_init( &thermo, &cfg );

    if ( thermo_check_fault( &thermo ) )
    {
        display_error_msg();
    }
    else
    {
        log_printf( &logger, "Status OK\r\n" );
    }
}

void application_task ( void )
{
    temperature = thermo_get_temperature( &thermo );

    log_printf( &logger, "Temperature : %f\r\n", temperature );

}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}


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

Additional Support

Resources

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