Build a simple temperature detector using TMP127 and PIC18LF45K80

Is it too hot or too cold?

Published Nov 01, 2023

Click board™

Thermo 25 Click

Dev Board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18LF45K80

Detects and measures the warmth or coolness of your surroundings

Hardware Overview

How does it work?

Thermo 25 Click is based on the TMP127-Q1, a factory-calibrated digital output temperature sensor designed for thermal management and thermal protection applications from Texas Instruments. This sensor is characterized by high accuracy and a temperature range of -55°C to +150°C that provides typical ±0.8°C accuracy. It also contains a 14-bit ADC to monitor and digitize the temperature reading to a resolution of 0.03125°C per LSB. The wide supply voltage range, low supply current, and SPI-compatible interface make it ideal for various applications, including process control, environmental monitoring, domestic appliances, and many more. The TMP127-Q1 possesses two operational modes: Continuous-Conversion (CC) and

Shutdown Mode. In the CC mode, ADC performs continuous temperature conversions and stores each result in the temperature register, overwriting the result from the previous conversion. The Shutdown mode reduces power consumption in the TMP127-Q1 when continuous temperature monitoring is not required. The TMP127-Q1 continuously powers up in the Continuous-Conversion mode, while the Shutdown mode can optimize current consumption for low-power applications. This Click board™ communicates with MCU through a standard SPI interface (compatible with SPI or MICROWIRE bus specifications) supporting the two most common SPI modes, SPI Mode 0 and 3,

with a maximum frequency of 10MHz. The SPI interface features a simplified no-register map protocol with a read-write 4-wire configuration. Writing to the TMP127-Q1 will allow the system to use the Shutdown mode and read the device ID. 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.

Features overview

Development board

EasyPIC v7 is the seventh generation of PIC development boards specially designed to develop embedded applications rapidly. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB-B. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyPIC v7 allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of

the EasyPIC v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use various external power sources, including an external 12V power supply, 7-23V AC or 9-32V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B) connector. Communication options such as

USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from PIC10F, PIC12F, PIC16F, PIC16Enh, PIC18F, PIC18FJ, and PIC18FK families. EasyPIC v7 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.

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

3648

Used MCU Pins

mikroBUS™ mapper

RST

SPI Chip Select

RE0

SPI Clock

RC3

SCK

SPI Data OUT

RC4

MISO

SPI Data IN

RC5

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

SCL

SDA

Power Supply

Ground

GND

Take a closer look

Schematic

Step by step

Project assembly

EasyPIC v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7 as your development board.

NECTO Output Selection Step Image hardware assembly

In the advanced settings, pay special attention to the Redirect standard output field. By default, it is set to Application output as the method of displaying final results. To show results via a UART terminal, select the “UART” option in that field and click the “SAVE” button. You will be returned to the Compiler field, and now you can move on to the next step by pressing the “NEXT” button.

Buck 22 Click front image hardware assembly

EasyPIC v7 MB 1 - upright/background hardware assembly

NECTO Compiler Selection Step Image hardware assembly

Necto DIP image step 7 hardware assembly

EasyPIC PRO v7a Display Selection Necto Step 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.

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.

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".

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.

Software Support

Library Description

This library contains API for Thermo 25 Click driver.

Key functions:

thermo25_check_communication This function sets the operating mode to shutdown, then reads and verifies the device ID and switches back to the continuous mode.
thermo25_read_temperature This function reads the temperature measurements in degrees Celsius.
thermo25_set_mode This function sets the device operating mode to shutdown or continuous mode by using SPI serial interface.

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 Thermo 25 Click example
 *
 * # Description
 * This example demonstrates the use of Thermo 25 click board by reading and displaying
 * the temperature measurements.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and logger, and checks the communication by setting the operating mode
 * to shutdown, reading and verifying the device ID, and switching back to the continuous mode.
 *
 * ## Application Task
 * Reads the temperature measurement in degrees Celsius and displays the results on the USB UART
 * approximately once per second.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "thermo25.h"

static thermo25_t thermo25;
static log_t logger;

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    thermo25_cfg_t thermo25_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.
    thermo25_cfg_setup( &thermo25_cfg );
    THERMO25_MAP_MIKROBUS( thermo25_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == thermo25_init( &thermo25, &thermo25_cfg ) )
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( THERMO25_ERROR == thermo25_check_communication ( &thermo25 ) )
    {
        log_error( &logger, " Check communication." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void )
{
    float temperature;
    if ( THERMO25_OK == thermo25_read_temperature ( &thermo25, &temperature ) )
    {
        log_printf ( &logger, " Temperature: %.2f degC\r\n\n", temperature );
        Delay_ms ( 1000 );
    }
}

void main ( void )
{
    application_init( );

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

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