Intermediate
30 min

Personalized oxygen tracking with VCNL4020C and PIC18F57Q43

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Oximeter 3 Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

Oximeter 3 Click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Upgrade your solution's health monitoring capabilities with innovative optical pulse oximetry technology

A

A

Hardware Overview

How does it work?

Oximeter 3 Click is based on the VCNL4020C-GS08, a fully integrated biosensor and ambient light sensor with an I2C interface from Vishay Semiconductor. The VCNL4020C-GS08 sensor has a built-in infrared emitter and signal processing IC in a single package with a 16-bit ADC. It also has an ambient light PIN photodiode with close-to-human-eye sensitivity with excellent ambient light suppression through signal modulation. For biosensor functionality, it converts the current from the PIN photodiode to a 16-bit digital data output value, while for ambient light sensing, it converts the current from the ambient light detector, amplifies it, and converts it to a 16-bit digital output stream. The integrated infrared emitter has a peak wavelength of 890nm. It emits light that reflects off an object within 20cm of the sensor and has a programmable drive current from 10mA to 200mA in 10mA steps. The built-in infrared emitter and broader sensitivity

photodiode also can work with the additional onboard green LED and IRLED as designed on this Click board™. As an additional light source, true green color LED (VLMTG1300) with a 525nm peak wavelength is used alongside an infrared dual-color emitting diode (VSMD66694) with 660nm and 940nm peak wavelength well suited for measuring the optical pulse oximetry. The PIN photodiode receives the light reflected off the object and converts it to a current. It has a peak sensitivity of 890nm, matching the peak wavelength of the emitter, and it is insensitive to ambient light. The VCNL4020C also provides ambient light sensing to support conventional backlight and display brightness auto-adjustment. The ambient light sensor receives the visible light and converts it to a current, and it has peak sensitivity at 540nm and bandwidth from 430nm to 610nm. Oximeter 3 Click communicates with the MCU using the standard I2C

2-wire interfacewith a fixed address compatible with all I2C modes (Standard, Fast, and High-Speed).  It allows easy access to a biosensor signal and light intensity measurements without complex calculations or programming. It also generates a programmable interrupt signal routed on the INT pin of the mikroBUS™, which offers Wake-Up functionality for the MCU when a proximity event or ambient light change occurs, which reduces processing overhead by eliminating the need for continuous polling. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the 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.

Oximeter 3 Click top side image
Oximeter 3 Click lateral side image
Oximeter 3 Click bottom side image

Features overview

Development board

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

48

RAM (Bytes)

8196

You complete me!

Accessories

Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.

Curiosity Nano Base for Click boards accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
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
Interrupt
PA6
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PB2
SCL
I2C Data
PB1
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Oximeter 3 Click Schematic schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Curiosity Nano Base for Click boards front image hardware assembly
Charger 27 Click front image hardware assembly
PIC18F47Q10 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Curiosity Nano with PICXXX Access 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 image step 5 hardware assembly
Necto image step 6 hardware assembly
PIC18F57Q43 Curiosity MCU Step 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

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 Oximeter 3 Click driver.

Key functions:

  • void oximeter3_generic_write ( uint8_t reg_addr, uint8_t write_data ) - Function for writing data to register address.
  • uint8_t oximeter3_generic_read ( uint8_t reg_addr ) - Function for reading data from register address.
  • uint16_t oximeter3_read_value ( uint8_t type_macro ) - Function for reading value from sensor.

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 
 * \brief Oximeter3 Click example
 * 
 * # Description
 * This example demonstrates the use of Oximeter 3 Click board.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes the driver, checks the device ID then configures the device for the selected mode.
 * 
 * ## Application Task  
 * Depending on the selected mode it reads heart rate data (OXIMETER3_HEART_RATE mode) or
 * values of proximity and ambient light sensor (OXIMETER3_PROX or OXIMETER3_ALS modes).
 * All data is being logged on USB UART where you can track their changes.
 * 
 * @note
 * In the case of heart rate, please use a Serial Plot application for data plotting.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "oximeter3.h"

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

static oximeter3_t oximeter3;
static log_t logger;

uint8_t dev_mode = 0;
uint16_t rd_val = 0;
uint16_t counter = 2500;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    oximeter3_cfg_t cfg;

    uint8_t dev_status;

    /** 
     * 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.

    oximeter3_cfg_setup( &cfg );
    OXIMETER3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    oximeter3_init( &oximeter3, &cfg );

    dev_status = oximeter3_generic_read( &oximeter3, OXIMETER3_REG_PRODUCT_ID );
    
    if ( dev_status != OXIMETER3_ID_VAL )
    {
        log_printf( &logger, " *****  ERROR!  ***** \r\n" );
        for ( ; ; );
    }

    dev_mode = OXIMETER3_HEART_RATE;
    
    oximeter3_generic_write( &oximeter3, OXIMETER3_REG_COMMAND,
                                         OXIMETER3_CMD_MEASUREMENT_DISABLE );
    
    oximeter3_generic_write( &oximeter3, OXIMETER3_REG_INTERRUPT_CTRL,
                                         OXIMETER3_INT_STATUS_PROX );
    
    if ( OXIMETER3_HEART_RATE == dev_mode )
    {
        oximeter3_generic_write( &oximeter3, OXIMETER3_REG_LED_CURRENT, 
                                             OXIMETER3_LED_CURR_MID );
        oximeter3_generic_write( &oximeter3, OXIMETER3_REG_PROX_MODULATOR_TIMING,
                                             OXIMETER3_PROX_TIMING_FREQ_390p625_KHZ );
    }
    else
    {
        oximeter3_generic_write( &oximeter3, OXIMETER3_REG_LED_CURRENT, 
                                             OXIMETER3_LED_CURR_MIN );
        oximeter3_generic_write( &oximeter3, OXIMETER3_REG_PROX_MODULATOR_TIMING,
                                             OXIMETER3_PROX_TIMING_FREQ_3p125_MHZ );
    }
    
    oximeter3_generic_write( &oximeter3, OXIMETER3_REG_PROX_RATE,
                                         OXIMETER3_PROX_RATE_250_MPS );

    oximeter3_generic_write( &oximeter3, OXIMETER3_REG_COMMAND,
                                         OXIMETER3_CMD_MEASUREMENT_ENABLE |
                                         OXIMETER3_CMD_PROX_PERIODIC_MEASUREMENT_ENABLE |
                                         OXIMETER3_CMD_ALS_PERIODIC_MEASUREMENT_ENABLE );

    log_printf( &logger, " ***** APP TASK ***** \r\n" );
}

void application_task ( void )
{
    if ( OXIMETER3_HEART_RATE == dev_mode )
    {
        if( !oximeter3_get_int_status( &oximeter3 ) )
        {
            rd_val = oximeter3_read_value( &oximeter3, OXIMETER3_PROX );
            oximeter3_generic_write( &oximeter3, OXIMETER3_REG_INTERRUPT_STATUS, 
                                                 OXIMETER3_INT_STATUS_PROX );
            
            counter++;
            if ( rd_val > 10000 )
            {
                log_printf( &logger, "%u\r\n", rd_val );
                counter = 2500;
            }
            else if ( counter > 2500 )
            {
                log_printf( &logger, "Please place your index finger on the sensor.\r\n" );
                counter = 0;
            }
        }
    }
    else if ( OXIMETER3_PROX == dev_mode || OXIMETER3_ALS == dev_mode )
    {
        if( !oximeter3_get_int_status( &oximeter3 ) )
        {
            rd_val = oximeter3_read_value( &oximeter3, OXIMETER3_PROX );
            oximeter3_generic_write( &oximeter3, OXIMETER3_REG_INTERRUPT_STATUS, 
                                                 OXIMETER3_INT_STATUS_PROX );
            
            log_printf( &logger, " * Proximity: %u \r\n", rd_val );
        
            rd_val = oximeter3_read_value( &oximeter3, OXIMETER3_ALS );
            log_printf( &logger, " * ALS: %u \r\n", rd_val );
            
            log_printf( &logger, "******************** \r\n" );
            
            Delay_ms( 500 );
        }
    }
}

void main ( void )
{
    application_init( );

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

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

Additional Support

Resources

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