Intermediate
30 min

Combine TPS62869 and STM32F429NI to accomplish the step-down conversion

It is true. These low values are real!

Buck 22 Click with UNI Clicker

Published Feb 26, 2023

Click board™

Buck 22 Click

Dev Board

UNI Clicker

Compiler

NECTO Studio

MCU

STM32F429NI

Step down voltage in the most efficient way

A

A

Hardware Overview

How does it work?

Buck 22 Click is based on the TPS62869, a synchronous step-down converter with an I2C interface from Texas Instruments. The TPS62869 base its work on the DCS-Control™ topology and operates in PWM (pulse width modulation) mode for medium to heavy load conditions and Power Save Mode at light load currents. In PWM mode, the converter operates with its nominal switching frequency of 2.4MHz, having a controlled frequency variation over the input voltage range from the VIN terminal from 2.4 up to 5.5V. The DCS-Control™ topology supports both operation modes (PWM and PFM selectable through a serial interface. The transition from PWM mode to Power Save Mode is  seamless and without effects on the

output voltage, providing an efficient, adaptive, and high power-density solution. With its DCS-Control™ architecture, excellent load transient performance and tight output voltage accuracy are achieved alongside adjustable output voltage and current ranges from 0.8V to 3.35V and up to 6A on the VOUT terminal with a 10mV step size. As the load current decreases, the TPS62869 enters Power Save Mode operation, which occurs when the inductor current becomes discontinuous, reaching 0A during a switching cycle. In Power Save Mode, the output voltage rises slightly above the nominal output voltage. This Click board™ communicates with MCU using the standard I2C 2-Wire interface to read data and configure

settings, supporting a Fast Mode operation up to 400kHz. Besides, it also possesses the power-good function, routed to the red LED marked as PWR and INT pin of the mikroBUS™ socket, indicating that the output reached regulation. 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.

Buck 22 Click hardware overview image

Features overview

Development board

UNI Clicker is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It supports a wide range of microcontrollers, such as different ARM, PIC32, dsPIC, PIC, and AVR from various vendors like Microchip, ST, NXP, and TI (regardless of their number of pins), four mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a debugger/programmer connector, and two 26-pin headers for interfacing with external electronics. Thanks to innovative manufacturing technology, it allows you to build

gadgets with unique functionalities and features quickly. Each part of the UNI Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the UNI Clicker programming method, using a third-party programmer or CODEGRIP/mikroProg connected to onboard JTAG/SWD header, the UNI Clicker board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Type-C (USB-C) connector, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or using a Li-Po/Li

Ion battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board (plus USB HOST/DEVICE), including the well-established mikroBUS™ socket, a standardized socket for the MCU card (SiBRAIN standard), and several user-configurable buttons and LED indicators. UNI Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI clicker double image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

ARM Cortex-M4

MCU Memory (KB)

2048

Silicon Vendor

STMicroelectronics

Pin count

216

RAM (Bytes)

262144

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
Power-Good Indicator
PG11
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PF1
SCL
I2C Data
PF0
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

Buck 22 click schematic schematic

Step by step

Project assembly

UNI Clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI Clicker as your development board.

UNI Clicker front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
UNI Clicker Access MB 1 - 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
Necto image step 7 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 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.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for Buck 22 Click driver.

Key functions:

buck22_set_vout - This function sets the output voltage by using I2C serial interface.

buck22_read_vout - This function reads the output voltage by using I2C serial interface.

buck22_get_pg_pin - This function returns the power good (PG) pin logic state.

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 Buck 22 Click example
 *
 * # Description
 * This example demonstrates the use of Buck 22 click by changing the output voltage.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and sets the control settings.
 *
 * ## Application Task
 * Changes the output voltage every 3 seconds and displays on the USB UART
 * the currently set voltage output value. It also checks the power good pin indicator.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "buck22.h"

static buck22_t buck22;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    buck22_cfg_t buck22_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.
    buck22_cfg_setup( &buck22_cfg );
    BUCK22_MAP_MIKROBUS( buck22_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == buck22_init( &buck22, &buck22_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( BUCK22_ERROR == buck22_set_control ( &buck22, BUCK22_CONTROL_DEFAULT_SETTING ) )
    {
        log_error( &logger, " Set control." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    if ( !buck22_get_pg_pin ( &buck22 ) )
    {
        log_info ( &logger, " Device is shut down. " );
        while ( !buck22_get_pg_pin ( &buck22 ) );
        log_info ( &logger, " Device is powered up. " );
    }
    static uint16_t vout_mv = BUCK22_VOUT_MIN;
    if ( BUCK22_OK == buck22_set_vout ( &buck22, vout_mv ) )
    {
        if ( BUCK22_OK == buck22_read_vout ( &buck22, &vout_mv ) )
        {
            log_printf ( &logger, " Vout: %u mV\r\n", vout_mv );
        }
    }
    vout_mv += 100;
    if ( vout_mv > BUCK22_VOUT_MAX )
    {
        vout_mv = BUCK22_VOUT_MIN;
    }
    Delay_ms ( 3000 );
}

void main ( void ) 
{
    application_init( );

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

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

Additional Support

Resources

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