Beginner
10 min

Maintain ideal temperature conditions with MAX31855K and MK20DX128VFM5

Thermocouple-to-digital converter

THERMO Click with UNI-DS v8

Published Jun 18, 2023

Click board™

THERMO Click

Development board

UNI-DS v8

Compiler

NECTO Studio

MCU

MK20DX128VFM5

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

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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

UNI-DS 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 STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR 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, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS 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. UNI-DS 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.

UNI-DS v8 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

ARM Cortex-M4

MCU Memory (KB)

160

Silicon Vendor

NXP

Pin count

32

RAM (Bytes)

16384

You complete me!

Accessories

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
PD6
RST
SPI Select / ID COMM
PD7
CS
SPI Clock
PC5
SCK
SPI Data OUT
PC7
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

Schematic

THERMO 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 UNI-DS v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN 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 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 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

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

/*!
 * \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 );

}

void main ( void )
{
    application_init( );

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


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

Additional Support

Resources