Beginner
10 min

Design a receiver in a 4-20mA current loop standard with INA196 and PIC32MZ2048EFM100

Receive and interpret the current signal

4-20 mA R Click with Curiosity PIC32 MZ EF

Published Jan 31, 2024

Click board™

4-20 mA R Click

Dev. board

Curiosity PIC32 MZ EF

Compiler

NECTO Studio

MCU

PIC32MZ2048EFM100

Compact and efficient solution for receiving and monitoring current in industrial systems

A

A

Hardware Overview

How does it work?

4-20mA R Click is based on the INA196, a current shunt monitor with a voltage output from Texas Instruments. The INA196 can sense drops across a shunt at a range of voltages without interference with its supply voltage and uses 500KHz bandwidth in current control loops. The 4-20mA R Click receives output current from 4 to 20mA from a compatible transmitter and converts it into low voltage. The transmitted loop current on this board comes directly to the load side of the INA196 shunt resistor from a VLOOP screw terminal. The

differential input voltage to the INA196 supply side comes from a TPS61041, a DC/DC boost converter from Texas Instruments. By default configuration, it provides a 16V and can be enabled over the EN pin of the mikroBUS™ socket. In addition, by replacing the R2 0ohm resistor with other values, it can also convert other voltages. The output of the INA196 then comes to the MCP3201, a 12-bit ADC from the Microchip. It communicates with the host microcontroller over an SPI serial interface of the mikroBUS™ socket, with the referent voltage of

2.048V. The ADC receives its reference from the MAX6106, a voltage reference LDO from Analog Devices. This Click board™ can operate either with 3.3V or 5V logic voltage levels selected via the PWR SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to 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.

4-20 mA R Click hardware overview image

Features overview

Development board

Curiosity PIC32 MZ EF development board is a fully integrated 32-bit development platform featuring the high-performance PIC32MZ EF Series (PIC32MZ2048EFM) that has a 2MB Flash, 512KB RAM, integrated FPU, Crypto accelerator, and excellent connectivity options. It includes an integrated programmer and debugger, requiring no additional hardware. Users can expand

functionality through MIKROE mikroBUS™ Click™ adapter boards, add Ethernet connectivity with the Microchip PHY daughter board, add WiFi connectivity capability using the Microchip expansions boards, and add audio input and output capability with Microchip audio daughter boards. These boards are fully integrated into PIC32’s powerful software framework, MPLAB Harmony,

which provides a flexible and modular interface to application development a rich set of inter-operable software stacks (TCP-IP, USB), and easy-to-use features. The Curiosity PIC32 MZ EF development board offers expansion capabilities making it an excellent choice for a rapid prototyping board in Connectivity, IOT, and general-purpose applications.

Curiosity PIC32MZ EF double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC32

MCU Memory (KB)

2048

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

524288

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
RPD4
CS
SPI Clock
RPD1
SCK
SPI Data OUT
RPD14
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Enable
RF13
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

4-20 mA R Click Schematic schematic

Step by step

Project assembly

Curiosity PIC32MZ EF front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity PIC32 MZ EF as your development board.

Curiosity PIC32MZ EF front image hardware assembly
GNSS2 Click front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
Curiosity PIC32 MZ EF MB 1 Access - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Curiosity PIC32 MZ EF MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

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 R Click driver.

Key functions:

  • c420mar_read_data - This function reads the 16-bit current value from the SPI data register, and then normalizes and converts it to float

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 420MaR Click example
 * 
 * # Description
 * This example showcases how to initialize, configure and use the 4-20 mA R click. It is a
 * simple SPI communication module that acts as a receiver in a 4-20 current loop. The click
 * reads current data and converts the analog signal to a digital 12-bit format.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * This function initializes and configures the logger and click modules.
 * 
 * ## Application Task  
 * This function reads and displays current data every half a second.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "c420mar.h"

// ------------------------------------------------------------------ VARIABLES

static c420mar_t c420mar;
static log_t logger;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( )
{
    log_cfg_t log_cfg;
    c420mar_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.

    c420mar_cfg_setup( &cfg );
    c420MAR_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    c420mar_init( &c420mar, &cfg );
}

void application_task ( )
{
    float current;

    current = c420mar_read_data( &c420mar );

    log_printf( &logger, "-----------------------------\r\n" );
    log_printf( &logger, " * Current: %.3f mA * \r\n", current );

    Delay_ms( 500 );
}

void main ( )
{
    application_init( );

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

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

Additional Support

Resources

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