Enhance your industrial processes with ADS1247 and STM32F072RB
RTDs - The path to temperature excellence
Published Oct 08, 2024
Click board™
RTD 2 Click
Dev. board
Nucleo 64 with STM32F072RB MCU
Compiler
NECTO Studio
MCU
STM32F072RB
Discover how our RTD solution can provide you with accurate and reliable temperature measurements for your critical processes.
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Hardware Overview
How does it work?
RTD 2 Click is based on the ADS1247, a highly integrated 24-bit data converter with a programmable gain amplifier (PGA) for sensor measurement applications from Texas Instruments. The ADS1247 includes a delta-sigma (ΔΣ) ADC with an adjustable single-cycle settling digital filter, an internal oscillator, and an SPI-compatible serial interface. It also has a flexible input multiplexer with system monitoring capability and general-purpose I/O settings, a very low-drift voltage reference, and two matched current sources for sensor excitation. The ADS1247 provides a system monitor function. This function can measure the analog power supply, digital power supply, external voltage reference, or ambient temperature. Note that the system monitor function provides a coarse result. When the system monitor is enabled, the analog inputs are disconnected. The two IDAC current sources integrated into the ADS1247 are used to implement the lead-wire compensation. One IDAC current source (IDAC1) provides excitation to the RTD element. The other current source (IDAC2)
has the same current setting, which cancels lead-wire resistance by generating a voltage drop across lead-wire resistance R2 equal to the voltage drop across the R1 resistor (9.09k). Because the voltage across the RTD is measured differentially at ADC pins AIN1 and AIN2 of the ADS1247, the voltages across the lead-wire resistances cancel. The ADC reference voltage (pins REFP0 and REFN0) is derived from the voltage across the R5 resistor with the currents from IDAC1 and IDAC2, providing ratiometric cancellation of current-source drift. R5 also level shifts the RTD signal to within the ADC-specified common-mode input range. The RTD 2 Click communicates with MCU using the standard SPI serial interface with an additional data-ready signal routed on the INT pin of the mikroBUS™ socket labeled as RDY. Data Ready signal indicates when a new conversion is complete, and the conversion result is stored in the conversion result buffer. It also has an active-low Reset signal routed on the RST pin of the mikroBUS™ used to reset the device and a precise conversion control signal routed on the AN pin of
the mikroBUS™ socket labeled as STR. The ADS1247 stays in Reset Mode as long as the RST pin stays low. When the RST pin goes high, the ADC comes out of Reset Mode and can convert data. This Click board™ can work only with 3-wire probe types that MIKROE offers, such as the PT100 type Platinum Probe, an RTD probe used to measure temperatures up to 250°C. Platinum is an excellent choice since they are very stable and reusable and are resistant to corrosion or oxidation. The measurement probe is connected to the RTD 2 Click by using the screw terminal on the top of the board, and it has wires that can be 1m long, which makes it possible to measure high temperatures from a safe distance. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.
Features overview
Development board
Nucleo-64 with STM32F072RB MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M0
MCU Memory (KB)
128
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
16384
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the STM32 Nucleo-64 board with our Click Shield for Nucleo-64, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
The PT100 3-wire temperature probe is an advanced RTD platinum sensor designed for precise temperature measurement up to 250°C. Perfectly compatible with the RTD Click board™, this probe utilizes RTD sensors - thermosensitive resistors that adapt their resistance to temperature changes. The probe's core features a meticulously crafted strip of platinum with a resistance of 100Ω at 0°C, earning the designation PT100. Key features include a temperature range of up to 250⁰ Celsius, a 3-wire configuration for enhanced accuracy, a length of 1m (100cm, 3.37 inches), Grade 2B construction for durability, and a tight tolerance of 0.5". Whether in industrial or scientific settings, the PT100 3-wire temperature probe delivers reliable and precise temperature readings, ensuring optimal performance in diverse applications.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Nucleo 64 with STM32F072RB MCU as your development board.
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 RTD 2 Click driver.
Key functions:
rtd2_check_new_data_ready- The function check new data readyrtd2_get_temperature- The function read output data and return ambient temperature from the PT100 3-wire temperature probertd2_enable_start- The function enables ADC conversion
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 Rtd 2 Click example
*
* # Description
* RTD 2 Click board is commonly used for measuring ambient temperature
* from the PT100 3-wire temperature probe.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver, performs a hardware reset, and sets the Click
* default configuration.
*
* ## Application Task
* Reads an ambient temperature measured by the PT100 3-wire temperature probe
* connected to the RTD 2 Click board, and logs the results on the USB UART each second.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "rtd2.h"
// ------------------------------------------------------------------ VARIABLES
static rtd2_t rtd2;
static log_t logger;
static float temperature;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
rtd2_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 ----" );
// Click initialization.
rtd2_cfg_setup( &cfg );
RTD2_MAP_MIKROBUS( cfg, MIKROBUS_1 );
rtd2_init( &rtd2, &cfg );
Delay_ms ( 200 );
log_printf( &logger, "----- Hardware Reset ------\r\n" );
rtd2_hw_reset( &rtd2 );
Delay_ms ( 100 );
log_printf( &logger, "-- Default configuration --\r\n" );
rtd2_default_cfg( &rtd2 );
Delay_ms ( 1000 );
log_printf( &logger, "--------------------------\r\n" );
log_printf( &logger, " Start Measurement \r\n" );
log_printf( &logger, "--------------------------\r\n" );
Delay_ms ( 100 );
}
void application_task ( void )
{
if ( rtd2_check_new_data_ready( &rtd2 ) == RTD2_NEW_DATA_IS_READY )
{
temperature = rtd2_get_temperature( &rtd2 );
log_printf( &logger, " Temperature : %.2f C\r\n", temperature );
log_printf( &logger, "--------------------------\r\n");
Delay_ms ( 1000 );
}
else
{
rtd2_enable_start( &rtd2, RTD2_START_CONVERSION_DISABLE );
Delay_ms ( 1000 );
}
}
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
