Design a transmitter in a 4-20mA current loop standard with XTR116 and MK64FN1M0VDC12
Transmit analog signals (like sensor data) over long distances in industrial settings
Published Jun 18, 2023
Click board™
4-20 mA T Click
Dev. board
Clicker 2 for Kinetis
Compiler
NECTO Studio
MCU
MK64FN1M0VDC12
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
Clicker 2 for Kinetis is a compact starter development board that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit ARM Cortex-M4F microcontroller, the MK64FN1M0VDC12 from NXP Semiconductors, two mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a JTAG programmer connector, and two 26-pin headers for interfacing with external electronics. Its compact design with clear and easily recognizable silkscreen markings allows you to build gadgets with unique functionalities and
features quickly. Each part of the Clicker 2 for Kinetis development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the Clicker 2 for Kinetis programming method, using a USB HID mikroBootloader or an external mikroProg connector for Kinetis programmer, the Clicker 2 board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Micro-B cable, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or
using a Li-Polymer battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, reset button, and several user-configurable buttons and LED indicators. Clicker 2 for Kinetis is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping 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
ARM Cortex-M4
MCU Memory (KB)
1024
Silicon Vendor
NXP
Pin count
121
RAM (Bytes)
262144
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 Clicker 2 for Kinetis 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
