Intermediate
30 min

Step into a new era of current sensing with INA282 and PIC18F26J53

Bidirectional current sensing evolved

Current 7 Click with EasyPIC v7

Published Dec 29, 2023

Click board™

Current 7 Click

Development board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18F26J53

Unleash the potential of accurate bidirectional current sensing with our solution, engineered to go beyond simple measurements. Empower your systems with the ability to monitor, analyze, and optimize power usage in both directions for unprecedented control.

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Hardware Overview

How does it work?

Current 7 Click is based on the INA381, a high-accuracy current-sensing amplifier from Texas Instruments. This voltage output current-sensing amplifier accurately measures voltages developed across the current-sensing resistor (also known as a current-shunt resistor) at a common-mode range that extends 14V below the negative supply rail as up to 80V, allowing for either low-side or high-side current sensing. The zero-drift topology enables high-precision measurements with maximum input offset voltages as low as 70μV over a wide temperature range. This Click board™ possesses two ways to communicate with the MCU. The analog output signal of the INA282 can be converted to a digital value using MCP3221, a successive approximation A/D converter with a 12-bit resolution from Microchip using a 2-wire I2C

compatible interface, or can be sent directly to an analog pin of the mikroBUS™ socket labeled as AN. The MCP3221 provides one single-ended input with low power consumption, a low maximum conversion current, and a Standby current of 250μA and 1μA, respectively. Data can be transferred at up to 100kbit/s in the Standard and 400kbit/s in the Fast Mode. Selection can be performed by onboard SMD jumper labeled as OUT SEL, setting it to an appropriate position marked as AN and ADC. The INA282 also allows a connection of external voltage signals on the onboard headers labeled REF1 and REF2 for the device’s reference voltage. This reference voltage determines how the output responds to certain input conditions. The configurable settings of the reference voltage control resistors, R5 and R6, allow the INA282 to

be used in unidirectional and bi-directional applications. More information about these operational modes can be found in the attached datasheet. This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. It allows both 3.3V and 5V capable MCUs to use the communication lines properly. Additionally, there is a possibility for the INA282 power supply selection via jumper labeled as PWR SEL to supply the INA282 from an external power supply terminal in the range from 2.7V to 18V or with mikroBUS™ power rails. 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.

Current 7 Click hardware overview image
Current 7 Click Current Warning image

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.

EasyPIC v7 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

64

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

3800

Used MCU Pins

mikroBUS™ mapper

Analog Output
RA3
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RC3
SCL
I2C Data
RC4
SDA
Power Supply
5V
5V
Ground
GND
GND
2

Take a closer look

Schematic

Current 7 Click Schematic 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.

EasyPIC v7 front image hardware assembly
LTE IoT 5 Click front image hardware assembly
MCU DIP 28 hardware assembly
LTE IoT 5 Click complete accessories setup image hardware assembly
EasyPIC v7 Access MB 2 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image 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.

UART Application Output Step 1

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.

UART Application Output Step 2

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".

UART Application Output Step 3

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.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Current 7 Click driver.

Key functions:

  • current7_read_voltage - This function reads raw ADC value and converts it to proportional voltage level

  • current7_get_current - This function reads the input current level [A] based on CURRENT7_NUM_CONVERSIONS of voltage measurements

  • current7_set_vref - This function sets the voltage reference for Current 7 Click driver

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 Current7 Click example
 *
 * # Description
 * This library contains API for Current 7 Click driver.
 * The demo application reads ADC value and current ( A ).
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes I2C or AN driver and log UART.
 * After driver initialization the app set default settings.
 *
 * ## Application Task
 * This is an example that demonstrates the use of the Current 7 Click board™.
 * In this example, we read and display the ADC values and current ( A ) data.
 * Results are being sent to the Usart Terminal where you can track their changes.
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "current7.h"

static current7_t current7;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;            /**< Logger config object. */
    current7_cfg_t current7_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.
    current7_cfg_setup( &current7_cfg );
    CURRENT7_MAP_MIKROBUS( current7_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == current7_init( &current7, &current7_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( CURRENT7_ERROR == current7_default_cfg ( &current7 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
    Delay_ms( 100 );
}

void application_task ( void ) 
{
    static float current;
    static uint16_t adc_val;
    
    current7_get_adc( &current7, &adc_val );
    log_printf( &logger, " ADC     : %d \r\n", adc_val );
    log_printf( &logger, "- - - - - - - - - - \r\n" );
    current7_get_current( &current7, &current );
    log_printf( &logger, " Current : %.3f A\r\n", current );
    log_printf( &logger, "--------------------\r\n" );
    Delay_ms( 1000 );
}

void main ( void ) 
{
    application_init( );

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

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

Additional Support

Resources