Monitor and respond to variations in light intensity using BH1620FVC and PIC18F27J13
Capturing lightscapes: The artistry of ambient sensor tech
Published Dec 29, 2023
Click board™
Ambient 12 Click
Dev. board
EasyPIC v7
Compiler
NECTO Studio
MCU
PIC18F27J13
Unveil the potential of our ambient light intensity sensing in autonomous systems, where it plays a crucial role in object recognition and environmental perception
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Hardware Overview
How does it work?
Ambient 12 Click is based on the BH1620FVC, an analog current-output ambient light sensor from Rohm Semiconductor. The BH1620FVC comprises photodiodes, amplifiers, and current mirror circuits, where the output current, in proportion to brightness, is converted to the voltage value by an external resistor. It is characterized by spectral sensitivity close to human eyes sensitivity with low sensitivity variations of +/-15%. It also has four configurable modes of operation: shutdown mode associated with three gain modes: high-gain
mode with an illuminance detection range of 1000lx, medium-gain mode up to 10.000lx, and low-gain mode up to 100.000lx. The desired gain mode is selected through CS and PWM pins of the mikroBUS™ socket labeled GC1 and GC2. The output voltage of the BH1620FVC can be converted to a digital value using MCP3221, a successive approximation A/D converter with a 12-bit resolution from Microchip, using a 2-wire I2C compatible interface, or can be sent directly to an analog pin of the mikroBUS™ socket labeled as
AN. Selection can be performed by onboard SMD jumper labeled as A/D SEL to an appropriate position marked as AN and ADC. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VIO 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)
128
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
3800
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ 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
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.
2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.
3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.
Software Support
Library Description
This library contains API for Ambient 12 Click driver.
Key functions:
ambient12_read_adc_voltage- This function reads raw 12-bit ADC data and converts it to voltage by using I2C serial interfaceambient12_voltage_to_lux- This function calculates illuminance (lux) based on the voltage inputambient12_set_gain_mode- This function sets the gain mode.
Open Source
Code example
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* @file main.c
* @brief Ambient 12 Click Example.
*
* # Description
* This example demonstrates the use of Ambient 12 click board.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and sets the gain mode to M-Gain which can detect the illuminance of up to 10000 lux.
*
* ## Application Task
* Reads the ADC voltage and then calculates the illuminance from it.
* The calculated value of illuminance in lux is being displayed on the USB UART approximately once per second.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "ambient12.h"
static ambient12_t ambient12; /**< Ambient 12 Click driver object. */
static log_t logger; /**< Logger object. */
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
ambient12_cfg_t ambient12_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 );
Delay_ms( 100 );
log_info( &logger, " Application Init " );
// Click initialization.
ambient12_cfg_setup( &ambient12_cfg );
AMBIENT12_MAP_MIKROBUS( ambient12_cfg, MIKROBUS_1 );
if ( ADC_ERROR == ambient12_init( &ambient12, &ambient12_cfg ) )
{
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
ambient12_set_gain_mode ( &ambient12, AMBIENT12_MODE_M_GAIN );
log_printf( &logger, " M-Gain mode selected.\r\n Up to 10000 lux can be measured.\r\n" );
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
float voltage = 0;
if ( AMBIENT12_OK == ambient12_read_adc_voltage ( &ambient12, &voltage ) )
{
log_printf( &logger, " Illuminance : %ld Lux\r\n\n", ambient12_voltage_to_lux( &ambient12, voltage ) );
}
Delay_ms( 1000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
