Customize and control your lighting with LT3755 and PIC18F4685
Smart choice for modern lighting applications
Published Nov 01, 2023
Click board™
LED Driver 17 Click
Dev Board
EasyPIC v7a
Compiler
NECTO Studio
MCU
PIC18F4685
With our LED driver solution, you can count on uninterrupted, reliable performance, guaranteeing that your lighting systems are always on when needed.
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Hardware Overview
How does it work?
LED Driver 17 Click is based on the LT3755, a highly efficient DC/DC controller from Analog Devices. This Click board™ is designed as a Buck mode LED driver with the ability to output 500mA, offering, in addition, PWM dimming functionality. The LTR3755, a highly efficient DC/DC controller, operates as a constant-current source and features onboard low-side external N-channel power MOSFETs, which are driven from an internal regulated supply and are capable of driving high-power 16V LEDs. Due to its high efficiency and reliable protection features, this board can be used in applications that require consistent and precise LED lighting control. It can also be used in applications that demand high power output,
such as commercial and industrial lighting. In terms of connectivity, this solution is designed to be controlled via the PWM pin of the mikroBUS™ socket to provide LED dimming control with ratios of up to 3000:1. In addition, the LT3755 also has a frequency adjust pin that allows the user to program the switching frequency from 100kHz to 1MHz. This feature is performed via an onboard R5 resistor, with the 800kHz set as the default value to optimize efficiency and performance. Other than the PWM pin, this Click board™ also features a fault pin labeled FLT, which is routed to the default interrupt INT position of the mikroBUS™ socket. This fault pin indicates any fault conditions to an external system, including overvoltage and
overcurrent protection. Besides information via the mikroBUS™ socket, the fault signal is visually indicated via a red LED labeled LD2. This LED Driver 17 Click supports an external power supply for the driver, which can be connected to the input terminal labeled VIN and should be within the range of 22V to 36V. 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 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.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
96
Silicon Vendor
Microchip
Pin count
40
RAM (Bytes)
3328
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the EasyPIC v7a as your development board.
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 LED Driver 17 Click driver.
Key functions:
leddriver17_get_fault_pin- This function returns the fault (FLT) pin logic state.leddriver17_set_duty_cycle- This function sets the PWM duty cycle in percentages ( Range[ 0..1 ] ).
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 LED Driver 17 Click example
*
* # Description
* This example demonstrates the use of LED Driver 17 click board by changing
* the LEDs dimming level.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and performs the click default configuration.
*
* ## Application Task
* Changes the LEDs dimming level by setting the PWM duty cycle every 500ms.
* The duty cycle percentage will be displayed on the USB UART. It also checks
* the fault indication pin and displays it accordingly.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "leddriver17.h"
static leddriver17_t leddriver17;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
leddriver17_cfg_t leddriver17_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.
leddriver17_cfg_setup( &leddriver17_cfg );
LEDDRIVER17_MAP_MIKROBUS( leddriver17_cfg, MIKROBUS_1 );
if ( PWM_ERROR == leddriver17_init( &leddriver17, &leddriver17_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( LEDDRIVER17_ERROR == leddriver17_default_cfg ( &leddriver17 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
static int8_t duty_cnt = 1;
static int8_t duty_inc = 1;
float duty = duty_cnt / 10.0;
if ( !leddriver17_get_fault_pin ( &leddriver17 ) )
{
log_printf( &logger, " Fault detected!\r\n" );
}
leddriver17_set_duty_cycle ( &leddriver17, duty );
log_printf( &logger, " Duty: %u%%\r\n\n", ( uint16_t ) ( duty_cnt * 10 ) );
Delay_ms( 500 );
if ( 10 == duty_cnt )
{
duty_inc = -1;
}
else if ( 0 == duty_cnt )
{
duty_inc = 1;
}
duty_cnt += duty_inc;
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
