Create a voltage balancer solution with MCP3202 and ATmega328

Overvoltage protection for 2 Li-Ion batteries

Published Feb 14, 2024

Click board™

Balancer 2 Click

Dev Board

Arduino UNO Rev3

Compiler

NECTO Studio

MCU

ATmega328

Perfect solution for voltage monitors, power tools, battery balancing, portable equipment, and instrumentation

Hardware Overview

How does it work?

Balancer 2 Click is Click board™ with two separate voltage battery monitoring circuitries, overvoltage supply detection, and automatic cell balancing. Balancer 2 Click monitors the voltages on each battery and corrects voltage differences. Combined with a LiPo/Li-Ion battery charger, this Click board™ can be used in a wide range of applications that benefit from reliable and efficient battery charging circuits. Balancer 2 Click is designed to balance two LiPo/Li-Ion batteries wired in serial. It contains all needed analog circuitry, made of two separate blocks, for each battery needed for the described device. Each block consists of one MOSFET, used as a power transistor - the Si7858BDP from Vishay. Besides the MOSFET, the circuit also contains a

transistor needed for automatic gate bias regulation based on the current running through the shunt resistors (R7 and R17). Each output is also optocoupled to ensure good reliability of the Click board™, regardless of the external power supply used. For that, EL357N-G photocouplers were used from Everlight. Two circuit blocks described above, combined, make the battery cell balancer. Besides that, this Click board™ has protection for the supply voltage. If the supply voltage exceeds 8.4V, the main P-Mosfet is powered off, and the battery is safe. The third part of the Balancer 2 Click is voltage monitoring circuitry based on the MCP3202, dual channel 12-bit A/D converter with SPI serial interface from Microchip. The cell voltages are brought to the

ADC input through the dedicated voltage dividers, which conditionate the voltage signal levels to ADC inputs. That way, the direct output voltage is achieved, so the user can switch the cell independently based on the voltage parameters read. 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. 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 2 Click hardware overview image

Features overview

Development board

Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an

ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the

first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.

Microcontroller Overview

MCU Card / MCU

Architecture

AVR

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

2048

You complete me!

Accessories

Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

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.

Used MCU Pins

mikroBUS™ mapper

Cell 1

PC0

Supply

PD2

RST

SPI Chip Select

PB2

SPI Clock

PB5

SCK

SPI Data OUT

PB4

MISO

SPI Data IN

PB3

MOSI

Power Supply

3.3V

Ground

GND

Cell 2

PD6

PWM

Status

PC3

INT

SCL

SDA

Power Supply

Ground

GND

Take a closer look

Schematic

Step by step

Project assembly

Click Shield for Arduino UNO front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.

Arduino UNO Rev3 front image hardware assembly

Charger 27 Click front image hardware assembly

Charger 27 Click complete accessories setup image hardware assembly

Arduino UNO Rev3 Access MB 1 - upright/background hardware assembly

Necto No Display image step 8 hardware assembly

Debug Image Necto Step hardware assembly

Track your results in real time

Application Output via Debug Mode

1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.

2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.

Software Support

Library Description

This library contains API for Balancer 2 Click driver.

Key functions:

balancer2_get_batttery_lvl - Function for getting real battery level
balancer2_adc_to_mv - Function for converting adc value to mV
balancer2_read_adc - Function for reading adc value

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 Balancer2 Click example
 * 
 * # Description
 * This application enable the batery charge. 
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Sets reference volatage of device, sets pins for supply and cells to high.
 * 
 * ## Application Task  
 * Every 2 seconds logs readings of battery mV lvl
 * 
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "balancer2.h"

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

static balancer2_t balancer2;
static log_t logger;

void application_init ( void )
{
    log_cfg_t log_cfg;
    balancer2_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.

    balancer2_cfg_setup( &cfg );
    BALANCER2_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    balancer2_init( &balancer2, &cfg );

    Delay_ms( 100 );
    log_printf( &logger, "--------------------\r\n" );
    log_printf( &logger, "  Balancer 2 Click  \r\n" );
    log_printf( &logger, "--------------------\r\n" );
    Delay_ms( 100 );
    balancer2_default_cfg ( &balancer2 );
    Delay_ms( 100 );
}

void application_task ( void )
{
    float battery;

    battery = balancer2_get_batttery_lvl( &balancer2, BALANCER2_BATT1 );
    log_printf( &logger, "Battery 1 : %f mV\r\n", battery );

    battery = balancer2_get_batttery_lvl( &balancer2, BALANCER2_BATT2 );
    log_printf( &logger, "Battery 2 : %f mV\r\n", battery );

    battery = balancer2_get_batttery_lvl( &balancer2, BALANCER2_BATT_BOTH );
    log_printf( &logger, "Batteries : %f mV\r\n", battery );

    log_printf( &logger, "__________________________________________\r\n" );

    Delay_ms( 2000 );
}

void main ( void )
{
    application_init( );

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


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