Design a transmitter in a 4-20mA current loop standard with XTR116 and STM32F031K6
Transmit analog signals (like sensor data) over long distances in industrial settings
Published Oct 01, 2024
Click board™
4-20 mA T Click
Dev. board
Nucleo 32 with STM32F031K6 MCU
Compiler
NECTO Studio
MCU
STM32F031K6
Achieve accurate current scaling and output limit functions within the 4-20mA current loop
A
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Hardware Overview
How does it work?
4-20mA T Click is based on the XTR116, a two-wire current transmitter from Texas Instruments. The XTR116 can provide accurate current scaling and output current limit functions with precision current output converters. It is designed to transmit analog 4 to 20mA signals over an industry-standard current loop. On this board, the output loop current from the XTR116 goes through the bridge rectifier to a VLOOP screw terminal. The diode bridge causes a 1.4V loss in loop supply voltage. Wide loop supply range can be between 7.5V and 36V
with a low span and nonlinearity error. As input offset voltages on the XTR116 are small, this board uses MCP4921, a 12-bit DAC from Microchip with optional 2x buffer output and an SPI interface. Thanks to the XTR116’s integrated power regulator and reference voltage block, the MCP4921 receives its power supply and the reference voltage necessary for correct data conversion. It communicates with the host MCU via three mikroBUS™ SPI lines over an isolator ADuM1411 from Analog Devices, a quad-channel 10Mbps data
rate digital isolator, to make sure higher voltages cannot harm the target microcontroller. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via an onboard jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this 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
Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The
board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,
and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M0
MCU Memory (KB)
32
Silicon Vendor
STMicroelectronics
Pin count
32
RAM (Bytes)
4096
You complete me!
Accessories
Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.
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 32 with STM32F031K6 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 4-20mA T Click driver.
Key functions:
c420mat_dac_output- This function sets the output of DACc420mat_set_i_out- This function sets the output current to selected value
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 C420mat Click example
*
* # Description
* This aplication changes the value of the output current.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes click SPI driver.
*
* ## Application Task
* Periodically changes Iout value.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "c420mat.h"
// ------------------------------------------------------------------ VARIABLES
static c420mat_t c420mat;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
c420mat_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.
c420mat_cfg_setup( &cfg );
C420MAT_MAP_MIKROBUS( cfg, MIKROBUS_1 );
c420mat_init( &c420mat, &cfg );
}
void application_task ( void )
{
c420mat_set_i_out( &c420mat, 56 ); // sets Iout to 5.6mA
Delay_ms( 3000 );
c420mat_set_i_out( &c420mat, 158 ); // sets Iout to 15.8mA
Delay_ms( 3000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
