Navigate the spectrum of colors with confidence using APDS-9250 and STM32G071RB
A world of colors, one sensing solution
Published Oct 08, 2024
Click board™
Color 9 Click
Dev Board
Nucleo 64 with STM32G071RB MCU
Compiler
NECTO Studio
MCU
STM32G071RB
With our color sensing solution, you can confidently address applications such as color matching, printing, and textile production, where precise color detection is paramount to success
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Hardware Overview
How does it work?
Color 9 Click is based on the APDS-9250, an integrated color sensor IC from Broadcom. This highly advanced four-channel color sensing device incorporates an IR blocking filter, that is used to block a portion of light in the IR spectrum, which can interfere with the readings of three independent photo-diodes, used to sense red, green and blue components of the light. However, it features an additional IR photo-sensing element, which is used to detect the intensity in the IR range. The IR measurement value can be used as a compensation parameter for the accurate color calculation. The color intensity sensing is roughly matched to the sensitivity of the human eye, so the sensor is the most sensitive in the range between 500nm and 600nm. The datasheet of the APDS-9250 offers an intensity over the wavelength diagram, so an accurate color calculation can be made in respect to the variable sensitivity of the sensor over the light wavelength. There are four independent A/D converters which are used to
digitize the color intensity in 18-bit resolution. The color and IR conversion results are available at the output registers in MSB/LSB format. Color 9 click communicates with the host MCU over the I2C interface, with its pin routed to the appropriate SCL and SDA pins of the mikroBUS™. The powerful interrupt engine allows more optimized firmware for the controller (MCU) to be written. The interrupt engine allows 16-bit values for the upper and lower threshold levels to be defined, as well as the persistence interval during which the event has occurred, before the interrupt is triggered, and more. Also, the user has the possibility to select which channel is included in the interrupt event detection.The APDS-9250 requires a very low number of external components. It requires only pull-up resistors for the I2C bus lines and the INT pin, which is an open-drain interrupt line. To allow for the best performance and most accurate measurements, the surface of the board and especially the
sensor IC itself, should always stay clean and without scratches, as dirt and moisture can after the light penetration through the filters. In addition, the manufacturer recommends that the angle of incidence stays less than 10° since the sensor IC has an aperture angle (beam width) of nearly 90°. If the angle of incidence is greater than advised, the filter shifting might occur, introducing distortion and affecting the measurement results. The spectral filters of this sensor are specialized for working with the broadband source of light, and measurement of the narrowband light sources should not be performed by this sensor. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.
Features overview
Development board
Nucleo-64 with STM32G071RB MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M0
MCU Memory (KB)
128
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
36864
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the STM32 Nucleo-64 board with our Click Shield for Nucleo-64, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
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 Nucleo 64 with STM32G071RB MCU as your development board.
Track your results in real time
Application Output via Debug Mode
1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.
2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.
Software Support
Library Description
This library contains API for Color 9 Click driver.
Key functions:
color9_get_green- This function gets Green measurement readingcolor9_get_blue- This function gets Blue measurement readingcolor9_get_red- This function gets Red measurement reading.
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 Color9 Click example
*
* # Description
* This application collects data from the sensor and logs green, blue and red
* measurement readings.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialize the driver and test if the sensor is
* present. If the ID read from the sensor is correct
* execute the initialization procedure.
*
* ## Application Task
* Wait for the color data to be available then read the data
* and send it to the serial port.
*
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "color9.h"
// ------------------------------------------------------------------ VARIABLES
static color9_t color9;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
color9_cfg_t cfg;
uint8_t id;
/**
* 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.
color9_cfg_setup( &cfg );
COLOR9_MAP_MIKROBUS( cfg, MIKROBUS_1 );
color9_init( &color9, &cfg );
id = color9_read( &color9, COLOR9_PART_ID );
if ( id == 0xB2 )
{
log_printf( &logger, "Register id 0x%x\r\n", id );
color9_meas_rate( &color9, COLOR9_LS_MEAS_BITWIDTH_13, COLOR9_LS_MEAS_RATE_1000ms );
color9_reg_ctrl( &color9, COLOR9_MAIN_CTRL_CS_MODE | COLOR9_MAIN_CTRL_LS_EN );
}
else
{
log_printf( &logger, "Error\r\n" );
while ( 1 );
}
}
void application_task ( void )
{
uint8_t conv_complete;
uint32_t measurement_data;
conv_complete = color9_get_status_reg( &color9 );
if ( conv_complete & 0x08 )
{
conv_complete = 0;
measurement_data = color9_get_Ir( &color9 );
log_printf( &logger, "Ir: %d\r\n", measurement_data );
measurement_data = color9_get_green( &color9 );
log_printf(&logger, "Green: %d\r\n", measurement_data);
measurement_data = color9_get_blue( &color9 );
log_printf(&logger, "Blue: %d\r\n", measurement_data);
measurement_data = color9_get_red( &color9 );
log_printf(&logger, "Red: %d\r\n", measurement_data);
}
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
