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Enhance energy efficiency with MLX75305 and PIC18F86K90 by tailoring illumination to the available natural light

Let there be light data

Ambient Click with UNI Clicker

Published Sep 16, 2023

Click board™

Ambient Click

Development board

UNI Clicker

Compiler

NECTO Studio

MCU

PIC18F86K90

Unlock the ability to monitor and control environmental conditions effortlessly, making your space more comfortable and energy-efficient

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Hardware Overview

How does it work?

Ambient Click is based on the MLX75305, a light-to-voltage SensorEyeC™ from Melexis Technologies. The MLX75305 is the second member of the SensorEyeC™ series of optical sensors designed for high-volume automotive, industrial, and consumer applications. It includes a photodiode, a trans-impedance amplifier to convert and amplify the photocurrent of the photodiode, and an open drain output buffer stage which gives a voltage value that varies

linearly with incident light, available on the AN pin of the mikroBUS™ socket. An internal configuration like this guarantees stable light responsivity over time and temperature and drastically improves noise behavior compared to discrete photodiode designs. Covering a spectral bandwidth from 500nm up to 1000nm, the MLX75305 maintains ±2% linearity across its whole output voltage range with a typical responsiveness of 70mV/(µW/cm²). Its unique features make it

suitable for measuring ambient light or controlling LED light in LCD backlight dimming applications. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR 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.

Ambient 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

PIC

MCU Memory (KB)

64

Silicon Vendor

Microchip

Pin count

80

RAM (Bytes)

3828

Used MCU Pins

mikroBUS™ mapper

Analog Output
PA0
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
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

Ambient 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
Thermo 28 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
UNI Clicker MB 1 - upright/with-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

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for Ambient Click driver.

Key functions:

  • ambient_read_an_pin_voltage - This function reads results of AD conversion of the AN pin and converts them to proportional voltage level

  • ambient_get_light_intensity - Calculates the light intensity from analog voltage measurement of the Melexis MLX75305 on Ambient Click

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 Ambient Click example
 * 
 * # Description
 * This application turns light intensity into voltage.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver enables GPIO,initializationADC, also write log.
 * 
 * ## Application Task  
 *  This is an example which demonstrates the use of Ambient click board.
 *  Ambient click reads ADC value and converts to light intensity [ uW/cm2 ].
 *  Results are being sent to the Usart Terminal where you can track their changes.
 *  All data logs on USB uart change for every 1 sec.
 *
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "ambient.h"

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

static ambient_t ambient;
static log_t logger;

uint16_t value_adc;
uint16_t light;

void application_init ( void )
{
    log_cfg_t log_cfg;
    ambient_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.

    ambient_cfg_setup( &cfg );
    AMBIENT_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    ambient_init( &ambient, &cfg );

    log_printf( &logger, "      Initialization ADC      " );
    Delay_ms( 100 );
}

void application_task ( void )
{
    ambient_data_t tmp;
    
    //  Task implementation.
    
    tmp = ambient_generic_read ( &ambient );
    light = ambient_calculate_light_intensity( &ambient, tmp, AMBIENT_VCC_3_3, AMBIENT_RES_12_BIT );

    log_printf( &logger, "** ADC value : [DEC]- %d, [HEX]- 0x%x \r\n", tmp, tmp );
    log_printf( &logger, "Light Intensity: %d uW/cm2 \r\n", light );

    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

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


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

Additional Support

Resources