Harness the full potential of proximity detection with VCNL36687S and STM32G474RE
Proximity sensing: Your personal digital security
Published Nov 08, 2024
Click board™
Proximity 8 Click
Dev. board
Nucleo 64 with STM32G474RE MCU
Compiler
NECTO Studio
MCU
STM32G474RE
Explore the uncharted territories of proximity detection and witness how it's shaping the technological landscape
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Hardware Overview
How does it work?
Proximity 8 Click is based on the VCNL36687S, a proximity sensor with VCSEL in a single package, with the I2C Interface from Vishay. This is a proximity sensor aimed towards portable, mobile and IoT applications, where close proximity detection is required. A good example might be a display activation in the close proximity of an operator. The sensor itself has an advanced analog and digital frontend circuits, which make it easy working with the sensor: it can be set to trigger a PS detection by a single operation over the I2C. The rest of the time, it will stay in the standby mode, saving the power that way. The VCNL36687S features a 12-bit ADC, therefore the output data is in 12-bit format. There are two registers that are used to hold the output result. Besides the four Most Significant Bits (MSBs), the PS data output high-byte register contains another bit that indicates that the device entered the sunlight protection mode. The operation of the VCNL36687S can be configured by writing to a set of CONFIG registers. There are four config registers, which are used to set the PS sampling
period, interrupt persistence value, smart persistence, interrupt, operating mode, etc. The comprehensive list of all the registers and their function is given within the VCNL36687S datasheet. However, Proximity 8 click supports a mikroSDK compatible library, which contains a set of functions used to simplify and accelerate the development. There are two pairs of threshold registers, used to trigger an interrupt when the measurement exceeds their values. These registers contain two 12-bit values, which represent the boundaries of the detection window. Each time one of these values is exceeded, an interrupt will be generated, and the INT pin will be asserted to a LOW logic level. The interrupt flag bit indicates the condition that caused an interrupt. The interrupt persistence can be set, preventing false triggering: the INT pin will be asserted only after a number of consecutive measurements that exceed either of the threshold values. This pin is routed to the mikroBUS™ INT pin, and it is normally pulled up by a resistor. Another feature of the VCNL36687S sensor is the Logic Output mode:
close proximity of an object will trigger an interrupt (a logic LOW level on the INT pin). When the object moves away, the INT pin will be de-asserted (a logic HIGH level on the INT pin). The difference between this mode and the other modes is that the user does not have to read the status bit to clear the interrupt and de-assert the INT pin. It will be controlled automatically by the low/high threshold values. To improve the reliability of the detection, the VCNL36687S employs a smart cancelation scheme. It uses the value stored within the register to subtract it from the output measurement, reducing the crosstalk phenomenon. A sunlight mode allows the device to be used even when exposed to sunlight. The VCNL36687S is operated by 1.8V, therefore a voltage regulator IC had to be used. The logic section of the VCNL36687S allows it to be operated at 3.3V directly, so no logic level translation is required if the Click board™ is used with MCUs that use 3.3V logic levels. However, if operated by an MCU that uses 5V for logic levels, a proper logic level voltage translation is required.
Features overview
Development board
Nucleo-64 with STM32G474R 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-M4
MCU Memory (KB)
512
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
128k
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
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Nucleo 64 with STM32G474RE MCU 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 Proximity 8 Click driver.
Key functions:
proximity8_generic_read- This function reads data from the desired registerproximity8_generic_write- This function writes data to the desired registerproximity8_get_interrupt_state- This function returns Interrupt state
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 Proximity8 Click example
*
* # Description
* This application enables usage of the proximity sensor
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization Driver init, test comunication and configuration chip for measurement
*
* ## Application Task
* Reads Proximity data and this data logs to the USBUART every 1500ms.
*
* *note:*
* The reading value and proximity of the data depend on the configuration.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "proximity8.h"
// ------------------------------------------------------------------ VARIABLES
static proximity8_t proximity8;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
proximity8_cfg_t cfg;
uint16_t tmp;
uint16_t w_temp;
/**
* 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.
proximity8_cfg_setup( &cfg );
PROXIMITY8_MAP_MIKROBUS( cfg, MIKROBUS_1 );
proximity8_init( &proximity8, &cfg );
//Test Communication
proximity8_generic_read( &proximity8, PROXIMITY8_REG_DEVICE_ID, &tmp );
if ( tmp == PROXIMITY8_DEVICE_ID )
{
log_printf( &logger, "---- Comunication OK!!! ----\r\n" );
}
else
{
log_printf( &logger, "---- Comunication ERROR!!! ----\r\n" );
for ( ; ; );
}
proximity8_default_cfg( &proximity8 );
log_printf( &logger, "---- Start measurement ----\r\n" );
}
void application_task ( void )
{
uint16_t proximity;
proximity8_generic_read( &proximity8, PROXIMITY8_REG_PROX_DATA, &proximity );
proximity = ( proximity & 0x7FFF );
log_printf( &logger, " Proximity data: %d\r\n", proximity );
log_printf( &logger, "-------------------------\r\n" );
Delay_ms( 1500 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
