Intermediate
30 min
0

Create an effective battery voltage balancer with MP2672A and PIC18F25J11

Automatic cell imbalance correction

Balancer 4 Click with EasyPIC v7

Published Dec 29, 2023

Click board™

Balancer 4 Click

Development board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18F25J11

Maintain the charge balance between batteries

A

A

Hardware Overview

How does it work?

Balancer 4 Click is based on the MP2672A, a highly integrated and flexible switch-mode battery charger for two-cell Lithium-Ion batteries in series from Monolithic Power Systems (MPS). The MP2672A features a cell balance function that monitors the voltage across each cell and equalizes them if the difference exceeds the mismatch threshold. It features up to 2A of programmable charge current for batteries with two cells in series, alongside protections like battery temperature monitoring, programmable charging safety timer protection, JEITA-compliant battery NTC monitoring, cell over-voltage protection (OVP), thermal regulation, and thermal shutdown. The MP2672A has a narrow voltage DC (NVDC) power structure. It automatically detects the battery voltage and charges it in three phases: pre-charge, constant current, and voltage charge. With a deeply discharged battery, the MP2672A regulates the system output to a minimum voltage level, which powers the system

instantly while simultaneously charging the battery via integrated FET. It also offers flexible new charging cycle initiation compatible with Standalone mode and Host-control mode of operation selectable through an onboard switch labeled as HOST SEL. Diverse and robust protections include a thermal regulation loop to decrease the charge current if the junction temperature exceeds the thermal loop threshold and battery temperature protection compliant with JEITA standards. Other safety features include input over-voltage protection (OVP), battery OVP, thermal shutdown, battery temperature monitoring, and a configurable backup timer to prevent prolonged charging of a dead battery. Balancer 4 Click communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting a Standard Mode operation up to 100kHz. It also has two LED indicators, red and green, marked with CHARGE and POWER, which can visually show

the existence of a good power supply to the MP2672A and the active status of the battery charging process. Also, an NTC function is available for temperature-qualified charging, where the MP2672A continuously monitors the battery’s temperature by measuring the voltage on the onboard NTC header pins. 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 MP2672A power supply selection via jumper labeled as VIN SEL to supply the MP2672A from an external power supply terminal in the range from 4V to 5.75V or with 5V voltage level from mikroBUS™ power rail. 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.

balancer-4-click-hardware-overview

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)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

3800

You complete me!

Accessories

Li-Polymer Battery is the ideal solution for devices that demand a dependable and long-lasting power supply while emphasizing mobility. Its compatibility with mikromedia boards ensures easy integration without additional modifications. With a voltage output of 3.7V, the battery meets the standard requirements of many electronic devices. Additionally, boasting a capacity of 2000mAh, it can store a substantial amount of energy, providing sustained power for extended periods. This feature minimizes the need for frequent recharging or replacement. Overall, the Li-Polymer Battery is a reliable and autonomous power source, ideally suited for devices requiring a stable and enduring energy solution. You can find a more extensive choice of Li-Polymer batteries in our offer.

Balancer 4 Click accessories image

Used MCU Pins

mikroBUS™ mapper

NC
NC
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

Balancer 4 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 Balancer 4 Click driver.

Key functions:

  • balancer4_write_register This function writes a desired data byte to the selected register by using I2C serial interface.

  • balancer4_write_and_verify_register This function writes a desired data byte to the selected register and verifies if it is written correctly by reading it.

  • balancer4_read_register This function reads a data byte from the selected register by using I2C serial interface.

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 Balancer4 Click example
 *
 * # Description
 * This example demonstrates the use of Balancer 4 click board by configuring
 * the click board for charging and then reading the status and fault registers.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and configures the click board for charging.
 *
 * ## Application Task
 * Reads and displays the status and fault registers on the USB UART every 500ms approximately.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "balancer4.h"

static balancer4_t balancer4;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    balancer4_cfg_t balancer4_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.
    balancer4_cfg_setup( &balancer4_cfg );
    BALANCER4_MAP_MIKROBUS( balancer4_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == balancer4_init( &balancer4, &balancer4_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( BALANCER4_ERROR == balancer4_default_cfg ( &balancer4 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    uint8_t status, fault;
    if ( BALANCER4_OK == balancer4_read_register ( &balancer4, BALANCER4_REG_STATUS, &status ) )
    {
        log_printf ( &logger, "\r\n - STATUS - \r\n", status );
        log_printf ( &logger, " Battery status: " );
        if ( status & BALANCER4_STATUS_BATTERY_MISSING )
        {
            log_printf ( &logger, "missing\r\n" );
        }
        else
        {
            log_printf ( &logger, "present\r\n" );
            log_printf ( &logger, " Charging status: " );
            switch ( status & BALANCER4_STATUS_CHG_STAT_MASK )
            {
                case BALANCER4_STATUS_NOT_CHARGING:
                {
                    log_printf ( &logger, "not charging\r\n" );
                    break;
                }
                case BALANCER4_STATUS_PRE_CHARGE:
                {
                    log_printf ( &logger, "pre-charge\r\n" );
                    break;
                }
                case BALANCER4_STATUS_CONSTANT_CHARGE:
                {
                    log_printf ( &logger, "constant current or constant voltage charge\r\n" );
                    break;
                }
                case BALANCER4_STATUS_CHARGING_COMPLETE:
                {
                    log_printf ( &logger, "charging complete\r\n" );
                    break;
                }
            }
        }
    }
    if ( BALANCER4_OK == balancer4_read_register ( &balancer4, BALANCER4_REG_FAULT, &fault ) )
    {
        if ( fault )
        {
            log_printf ( &logger, "\r\n - FAULT - \r\n" );
            if ( fault & BALANCER4_FAULT_WD )
            {
                log_printf ( &logger, " The watchdog timer has expired\r\n" );
            }
            if ( fault & BALANCER4_FAULT_INPUT )
            {
                log_printf ( &logger, " Input OVP has occured\r\n" );
            }
            if ( fault & BALANCER4_FAULT_THERMAL_SD )
            {
                log_printf ( &logger, " Thermal shutdown\r\n" );
            }
            if ( fault & BALANCER4_FAULT_TIMER )
            {
                log_printf ( &logger, " The safety timer has expired\r\n" );
            }
            if ( fault & BALANCER4_FAULT_BAT )
            {
                log_printf ( &logger, " Battery OVP has occured\r\n" );
            }
            switch ( fault & BALANCER4_FAULT_NTC_MASK )
            {
                case BALANCER4_FAULT_NTC_COLD:
                {
                    log_printf ( &logger, " An NTC cold fault has occured\r\n" );
                    break;
                }
                case BALANCER4_FAULT_NTC_COOL:
                {
                    log_printf ( &logger, " An NTC cool fault has occured\r\n" );
                    break;
                }
                case BALANCER4_FAULT_NTC_WARM:
                {
                    log_printf ( &logger, " An NTC warm fault has occured\r\n" );
                    break;
                }
                case BALANCER4_FAULT_NTC_HOT:
                {
                    log_printf ( &logger, " An NTC hot fault has occured\r\n" );
                    break;
                }
            }
        }
    }
    Delay_ms ( 500 );
}

void main ( void ) 
{
    application_init( );

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

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

Additional Support

Resources