Measure currents with the greatest precision using EMC1702 and PIC18LF46K80

Your journey to next-level measurement and insights

Published Nov 01, 2023

Click board™

Current 3 Click

Dev Board

EasyPIC v8

Compiler

NECTO Studio

MCU

PIC18LF46K80

Elevate safety and compliance in your operations with our current measurement solution, which facilitates accurate current monitoring, ensuring adherence to industry standards and regulations

Hardware Overview

How does it work?

Current 3 Click is based on the EMC1702, a combination of the high-side current sensing device with precision voltage and temperature measurement capabilities from Microchip. It measures the voltage developed across an external sense resistor to represent the high-side current of a battery or voltage regulator. It also measures the source voltage and uses these measured values to present a proportional power calculation. The EMC1702 contains additional bi-directional peak detection circuitry to flag instantaneous current spikes with programmable time duration and magnitude threshold. Also, it possesses an external diode channel for temperature measurement and an internal diode for ambient temperature measurements. The EMC1702 current-sense measurement converts differential input voltage measured across an

external sense resistor to a proportional output voltage. This voltage is digitized using a variable resolution (13-bit to 15-bit) Sigma-Delta ADC and I2C protocol. The current range allows for large variations in measured current with high accuracy and a low voltage drop across the resistor. Current 3 Click communicates with MCU using the standard I2C 2-Wire interface with a maximum frequency of 400kHz. The EMC1702 slave address is determined by a resistor connected R6 (0Ω) between the ground and the ADDR_SEL pin. Various values of this resistor also provide different slave addresses (0Ω is equal to 1001_100(r/w)). The EMC1702 has two levels of monitoring and contains user-programmable bipolar Full-Scale Sense Ranges (FSSR). Each VSENSE measurement is averaged over a user-programmable time. If VSENSE exceeds (or drops below) the respective

limits, the ALERT pin, routed on the INT pin of the mikroBUS™ socket labeled as ALT, may be asserted. It also contains user-programmable current peak detection circuitry on DUR_SEL and TH_SEL pins that will assert the THERM pin, routed on the RST pin of the mikroBUS™ socket labeled as TRM, if a current spike is detected larger than the programmed threshold and of longer duration than the programmed time (threshold and duration selected by resistors R7 and R8). This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL 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

EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC v8 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.

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

3648

Used MCU Pins

mikroBUS™ mapper

Current Peak Detection

RE1

RST

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

PWM

Interrupt

RB0

INT

I2C Clock

RC3

SCL

I2C Data

RC4

SDA

Power Supply

Ground

GND

Take a closer look

Schematic

Step by step

Project assembly

EasyPIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v8 as your development board.

NECTO Output Selection Step Image hardware assembly

In the advanced settings, pay special attention to the Redirect standard output field. By default, it is set to Application output as the method of displaying final results. To show results via a UART terminal, select the “UART” option in that field and click the “SAVE” button. You will be returned to the Compiler field, and now you can move on to the next step by pressing the “NEXT” button.

GNSS2 Click front image hardware assembly

GNSS2 Click complete accessories setup image hardware assembly

EasyPIC v8 Access DIPMB 1 - upright/background hardware assembly

NECTO Compiler Selection Step Image hardware assembly

Necto DIP image step 7 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.

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.

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".

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.

Software Support

Library Description

This library contains API for Current 3 Click driver.

Key functions:

current3_get_temperature - The function get the temperature by read multiple data bytes from a group of contiguous registers
current3_get_source_voltage - The function source voltage registers store the voltage measured at the SENSE+ pin
current3_get_current - The function current measurement measure the direction of current flow ( from SENSE+ to SENSE- or from SENSE- to SENSE+ )

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 
 * \brief Current3 Click example
 * 
 * # Description
 * Current 3 Click can be used to measure current ranging up to 8000mA, and display temperature, 
 * voltage and current data - using I2C comunication.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver enables - I2C,
 * check communication and set sense sampling configuration, also write log.
 * 
 * ## Application Task  
 * This is an example which demonstrates the use of Current 3  Click board.
 * Current 3 Click board can be used to measure current ranging
 * up to 8000mA, and display temperature, voltage and current data.
 * All data logs write on USB uart changes for every 2 sec.
 * 
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "current3.h"

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

static current3_t current3;
static log_t logger;
static current3_sense_cfg_data_t sense_cfg_data;

static float temperature;
static float voltage;
static float current;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    current3_cfg_t cfg;
    uint8_t read_data;

    /** 
     * 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.

    current3_cfg_setup( &cfg );
    CURRENT3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    current3_init( &current3, &cfg );

    Delay_ms( 100 );
    log_printf( &logger, "     Driver init. done     \r\n" );
    log_printf( &logger, "---------------------------\r\n" );
    
    current3_generic_read( &current3, CURRENT3_REG_PRODUCT_ID, &read_data, 1 );
    if ( read_data == CURRENT3_DEV_ID )
    {
        log_printf( &logger, "     Communication OK      \r\n" );
        log_printf( &logger, "---------------------------\r\n" );
    }
    else
    {
        log_printf( &logger, "    Communication ERROR    \r\n" );
        log_printf( &logger, "     Reset the device      \r\n" );
        log_printf( &logger, "---------------------------\r\n" );
        for ( ; ; );
    }
    
    current3_default_cfg( &current3, sense_cfg_data );
}

void application_task ( void )
{
    temperature = current3_get_temperature( &current3, CURRENT3_TEMP_INTERNAL_DIODE );
    log_printf( &logger, " Temperature = %.2f C\r\n", temperature );

    voltage = current3_get_source_voltage( &current3 );
    log_printf( &logger, " Voltage     = %.2f V\r\n", voltage );

    current = current3_get_current( &current3 );
    log_printf( &logger, " Current     = %.2f mA\r\n", current );
    log_printf( &logger, "---------------------------\r\n" );
    Delay_ms( 2000 );
}

void main ( void )
{
    application_init( );

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

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