30 min

Discover true colors with pinpoint chromatic accuracy using AS7263 and STM32F722VE

Experience the brilliance of true whites

Spectral 3 Click with UNI-DS v8

Published Sep 21, 2023

Click board™

Spectral 3 Click

Development board



NECTO Studio



Count on our multispectral light sensing solution for accurate, reliable, and real-time chromatic white color detection, ensuring the highest standards of color quality



Hardware Overview

How does it work?

Spectral 3 Click is based on the AS7263, a 6 channel NIR Spectral_ID device with electronic shutter and smart Interface. This is a very advanced multispectral sensor, which incorporates a 6 photodiodes array element. Every photo element is filtered through the Gaussian filters, implemented through the nano-optic deposited interference filter technology, designed to provide ranges for 6 near-IR spectral channels: R = 610nm, S = 680nm, T = 730nm, U = 760nm, V = 810nm and W = 860nm, each with 20nm FWHM. The filter characteristics are tested and measured with the diffused white light. This technology ensures minimal drift of the readings and temperature stability. It should be noted that the filter accuracy will be affected by the angle of incidence, determined by an integrated aperture and the internal microlenses, which is ±20° for the AS7263. The measurements from the photo elements are digitized by the 16bit ADC converter and processed by the Spectral_ID engine. Besides the raw values of the six color elements, the engine calculates all the calibrated values available on this device and outputs them as 32bit float values. After the specified integration time (2.8ms min), those values are available in their respective registers and are accessible via the smart high-level UART interface driven by simple AT commands, or the I2C communication protocol bus. Even the temperature sensor can be accessed

via its register. A complete list of all the available color coordinates and the registers which hold these values can be found in the AS7263 datasheet. The sensor data is organized in two banks. The first bank contains readings from the S, T, U and V photodiodes, while the second bank contains readings from the R, T, U, and W photodiodes. Different modes allow readings to be made from each bank, as well as the combinations between these two banks. There is also a mode for one-shot reading when time-critical or triggered measurement needs to be made. The photodiode letter codes above, represent the channels of the respective wavelengths (Channel R, Channel S, Channel T, and more). An interrupt can be triggered when the data is ready to be read by the host, depending on the selected bank mode. If the interrupt is enabled (INT = 1), the INT line is pulled to a LOW logic level and DATA_RDY bit of the control register is set to 1. The INT line is released when the control register is read. The DATA_RDY bit will be cleared whenever the measurement registers are read. The interrupt will be generated after one or more integrating cycles are completed, depending on the selected bank mode. The INT line of the AS7263 is routed to the mikroBUS™ INT pin and can be used to trigger an interrupt on the host MCU. More about bank reading modes and the interrupts can be found in the provided AS7263 datasheet. The RESET line of

the sensor is routed to the mikroBUS™ RST pin. If this line is pulled to a LOW level for more than 100ms, it will reset the device. The sensor firmware is kept externally, on the auxiliary flash memory IC. The AT25SF041, an SPI serial flash memory is used for storing the firmware of the AS7263 sensor. The AT25SF041 IC communicates with the sensor via the SPI lines, internally routed on the Spectral 3 click. UART and I2C lines of the AS7263 sensor are routed to the mikroBUS™ respective UART pins (RX/TX and SDA/SCL). To select which interface will be used to drive the sensor IC, three onboard SMD jumpers labeled as COM SEL need to be moved either to the left position (to enable UART), or to the right position (to enable I2C). It should be noted that all the SMD jumpers need to be moved at once - if some of them are set as UART and some as I2C, the communication might not be possible at all. There are two integrated programmable LED drivers on the AS7263 sensor. The first LED constant current driver can be programmed up to 10mA and it can be used as the status indicator. It is also activated during the sensor firmware programming. The second LED driver is intended for driving of the light source for the measurement surface illumination. It can drive high brightness LED with up to 100mA. Both of these LED drivers are available through the communication interfaces.

Spectral 3 Click hardware overview image

Features overview

Development board

UNI-DS v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR MCUs regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector. Communication options such as USB-UART, USB

HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. UNI-DS v8 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.

UNI-DS v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M7

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Power Supply
I2C Clock
I2C Data

Take a closer look


Spectral 3 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI-DS v8 as your development board.

Fusion for PIC v8 front image hardware assembly
Buck 22 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
v8 SiBRAIN MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

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.

UART Application Output Step 1

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.

UART Application Output Step 2

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".

UART Application Output Step 3

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.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Spectral 3 Click driver.

Key functions:

  • spectral3_module_reset - Reset module

  • spectral3_send_command - Send command

  • spectral3_get_data - Read raw X, Y, Z and NIR data as well as two special internal registers D, & C.

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 Spectral3 Click example
 * # Description
 * This example reads and processes data from Spectral 3 clicks.
 * The demo application is composed of two sections :
 * ## Application Init 
 * Initializes the driver and configures the sensor.
 * ## Application Task  
 * Reads the values of all 6 channels and parses it to the USB UART each second.
 * ## Additional Function
 * - spectral3_process ( ) - The general process of collecting the sensor responses.
 * \author MikroE Team
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "spectral3.h"
#include "string.h"


#define SPECTRAL3_CMD_AT        "AT" 
#define SPECTRAL3_CMD_GAIN      "ATGAIN=2"

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

static spectral3_t spectral3;
static log_t logger;

static char current_parser_buf[ PROCESS_PARSER_BUFFER_SIZE ];

// ------------------------------------------------------- ADDITIONAL FUNCTIONS

static void spectral3_process ( void )
    int32_t rsp_size;
    uint16_t rsp_cnt = 0;
    char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
    uint8_t check_buf_cnt;
    uint8_t process_cnt = PROCESS_COUNTER;
    // Clear parser buffer
    memset( current_parser_buf, 0 , PROCESS_PARSER_BUFFER_SIZE ); 
    while( process_cnt != 0 )
        rsp_size = spectral3_generic_read( &spectral3, &uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );

        if ( rsp_size > 0 )
            // Validation of the received data
            for ( check_buf_cnt = 0; check_buf_cnt < rsp_size; check_buf_cnt++ )
                if ( uart_rx_buffer[ check_buf_cnt ] == 0 ) 
                    uart_rx_buffer[ check_buf_cnt ] = 13;
            // Storages data in parser buffer
            rsp_cnt += rsp_size;
            if ( rsp_cnt < PROCESS_PARSER_BUFFER_SIZE )
                strncat( current_parser_buf, uart_rx_buffer, rsp_size );
            // Clear RX buffer
            memset( uart_rx_buffer, 0, PROCESS_RX_BUFFER_SIZE );
            // Process delay 
            Delay_100ms( );

static void parser_application ( )
    uint16_t read_data[ 6 ];

    spectral3_send_command( &spectral3, SPECTRAL3_CMD_DATA );
    spectral3_process( );

    spectral3_get_data( current_parser_buf, read_data );
    log_printf( &logger, "-- R value: %d \r\n", read_data[ 0 ] );   
    log_printf( &logger, "-- S value: %d \r\n", read_data[ 1 ] );
    log_printf( &logger, "-- T value: %d \r\n", read_data[ 2 ] );
    log_printf( &logger, "-- U value: %d \r\n", read_data[ 3 ] );
    log_printf( &logger, "-- V value: %d \r\n", read_data[ 4 ] );
    log_printf( &logger, "-- W value: %d \r\n", read_data[ 5 ] );
    log_printf( &logger, "-----------------\r\n" );

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
    log_cfg_t log_cfg;
    spectral3_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.

    spectral3_cfg_setup( &cfg );
    spectral3_init( &spectral3, &cfg );

    spectral3_module_reset( &spectral3 );
    Delay_ms( 500 );
    log_printf( &logger, "Configuring the sensor...\r\n" );
    spectral3_send_command( &spectral3, SPECTRAL3_CMD_AT );
    spectral3_process( );
    spectral3_send_command( &spectral3, SPECTRAL3_CMD_GAIN );
    spectral3_process( );
    spectral3_send_command( &spectral3, SPECTRAL3_CMD_MODE );
    spectral3_process( );
    log_printf( &logger, "The sensor has been configured!\r\n" );
    Delay_ms( 1000 );

void application_task ( void )
    parser_application( );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

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

Additional Support