Beginner
10 min

Manage and regulate power efficiently using MAX25232 and PIC18LF45K42

Ensure a consistent and reliable power supply

Step Down 8 Click with EasyPIC v7a

Published Nov 13, 2023

Click board™

Step Down 8 Click

Development board

EasyPIC v7a

Compiler

NECTO Studio

MCU

PIC18LF45K42

Our DC-DC converter promises not just a reduction in voltage but a surge in performance for your electronic applications.

A

A

Hardware Overview

How does it work?

Step Down 8 Click is based on the MAX25232, a mini buck converter from Analog Devices. The MAX25232 features an under-voltage lockout, a soft-start timer, an on-chip oscillator, skip-mode operation, output-voltage overshoot protection, thermal-overload protection, and many more features. This current-mode-controlled buck converter operates at a 2.1MHz frequency, which guarantees no AM band interference, while it can also operate at 400KHz for minimum switching losses and maximum efficiency. While maintaining a 3A output current, it can stay in dropout by running at a 99% duty cycle. Voltage quality can be monitored by the host MCU. To set the output voltage, this Click board™ uses the MCP4661, an 8-bit I2C digital potentiometer with non-volatile memory. It comes with 256 resistors

and 257 wiper positions, while the last position is stored in an EEPROM. By setting the wiper value of resistance, you can set the output voltage of the MAX25232 converter available on the VOUT terminal. The Step Down 8 Click also features an unpopulated 3-pin header that allows you to set an operation mode. If you connect the SYNC pin to a GND or leave it unconnected, the device operates in a highly efficient pulse-skipping mode. If you connect SYNC to a BIAS pin or apply a clock to it, the device is in a forced-PWM mode (FPWM). Switching of modes can be done during the operation. Step Down 8 Click uses a standard 2-Wire I2C interface of the MCP4661 to communicate with the host MCU, supporting 100KHz, 400KHz, and 3.4MHz frequencies. The I2C address can be set over the ADDR SEL jumpers,

where the 0 position is selected by default. There is an EN enable pin to enable the converter and a PG power good pin that allows you to monitor the voltage quality. The Spread-Spectrum feature is an option that can be enabled over the SPS pin, offered to improve the EMI performance of the device. It does not interfere with the external clock applied to the SYNC pin. 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.

Step Down 8 Click hardware overview image

Features overview

Development board

EasyPIC v7a is the seventh generation of PIC development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as the first-ever embedded debugger/programmer over USB-C. 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 v7a allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of the EasyPIC v7a 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 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-C (USB-C) 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 v7a 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 v7a double side image

Microcontroller Overview

MCU Card / MCU

PIC18LF45K42

Architecture

PIC

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Chip Enable
RE1
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Spread-Spectrum Enable
RC0
PWM
Power Good Indicator
RB0
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RC3
SCL
I2C Data
RC4
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

Step Down 8 Click Schematic schematic

Step by step

Project assembly

EasyPIC v7a front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7a as your development board.

EasyPIC v7a front image hardware assembly
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
EasyPIC v7a 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 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 Step Down 8 Click driver.

Key functions:

  • stepdown8_set_en_pin - Step Down 8 set EN pin state function.

  • stepdown8_set_wiper_pos - Step Down 8 set wiper position.

  • stepdown8_set_output - Step Down 8 set output voltage.

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 Step Down 8 Click example
 *
 * # Description
 * This library contains API for the Step Down 8 Click driver.
 * This driver provides the functions to set the output voltage treshold.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization of I2C module and log UART.
 * After driver initialization, default settings sets output voltage to 3 V.
 *
 * ## Application Task
 * This example demonstrates the use of the Step Down 8 Click board™ by changing 
 * output voltage every 2 seconds starting from 3 V up to 18 V.
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "stepdown8.h"

static stepdown8_t stepdown8;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    stepdown8_cfg_t stepdown8_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.
    stepdown8_cfg_setup( &stepdown8_cfg );
    STEPDOWN8_MAP_MIKROBUS( stepdown8_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == stepdown8_init( &stepdown8, &stepdown8_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( STEPDOWN8_ERROR == stepdown8_default_cfg ( &stepdown8 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }

    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    for ( uint8_t n_cnt = STEPDOWN8_MIN_OUTPUT; n_cnt <= STEPDOWN8_MAX_OUTPUT; n_cnt++ )
    {
        stepdown8_set_output( &stepdown8, ( float ) n_cnt );
        log_printf( &logger, " Output voltage %d V\r\n", ( uint16_t ) n_cnt );
        Delay_ms( 2000 );
    }
}

void main ( void ) 
{
    application_init( );

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

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

Additional Support

Resources