Enhance energy efficiency with MLX75305 and PIC18LF2620 by tailoring illumination to the available natural light
Let there be light data
Published Nov 01, 2023
Click board™
Ambient Click
Dev Board
EasyPIC v7
Compiler
NECTO Studio
MCU
PIC18LF2620
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.
Features overview
Development board
EasyPIC v7 is the seventh generation of PIC development boards specially designed to develop embedded applications rapidly. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB-B. 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 v7 allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of
the EasyPIC v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block 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-B (USB-B) 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 v7 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)
64
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
3968
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 v7 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 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 levelambient_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
