Determine if something is nearby or not using VCNL4035X01 and STM32F091RC

Proximity 5 Click is based on the VCNL4035X01, a fully integrated proximity and ambient light sensor with I2C interface and the interrupt function for gesture applications, from Vishay Semiconductors. This sensor features very advanced 16bit Ambient Light Sensor (ALS) which makes use of the proprietary Filtron™ technology, providing spectral response sensitivity near to human eye. The ALS sensor also effectively cancels out infrared light, has immunity to the flickering of fluorescent light sources and has a programmable detection range, with the resolution of up to 0.004 lux per count. The Proximity Sensing (PS) section of the VCNL4035X01 J IC implements several solutions for the improved proximity detection of objects of any color. It relies on detection of the reflected IR light from the emitting LEDs. Features such as the immunity to a red glow, intelligent crosstalk phenomenon reduction, smart persistence scheme, programmable IR LED current, and selectable sampling resolution, help in achieving a reliable and accurate proximity detection. The processed readings of the ALS and PS sections can be fetched from the respective registers via the I2C interface. The I2C bus lines are routed to the respective mikroBUS™ I2C pins:

SCL is the I2C clock and SDA is the I2C data line. The VCNL4035X01 J sensor IC integrates three independent LED drivers, which can drive the external IR LEDs with up to 200mA, allowing a wide range of external IR LEDs to be used. Proximity 5 click uses the VSMY2850RG LEDs, 850nm IR LEDs with lenses, from Vishay. These IR LEDs are operating within the wavelength range which is recommended by the sensor manufacturer. The IR LEDs can be driven by the variable duty cycle, which affects the total power consumption, as well as the PS response time. The VCNL4035X01 J sensor IC is powered by the 3.3V rail from the mikroBUS™ directly. However, since it uses the I2C communication protocol, it is possible to choose the voltage for the I2C pull-up resistors between 3.3V and 5V. This is accomplished by moving the SMD jumper labeled as VCCIO SEL to the appropriate position. This jumper allows communication with both 3.3V and 5V MCUs. Proximity 5 click offers programmable interrupt engine. The INT pin is routed to the mikroBUS™ INT pin and it is pulled up by the onboard resistor. When asserted, it is driven to a LOW logic level. The interrupt can be programmed for a wide range of events for both ALS and PS sections:

ALS threshold window with two 16bit values for the upper and lower threshold levels, ALS Persistence which affects the integration time before an interrupt is triggered. The PS section offers similar interrupt sources, with the addition of the object detection which triggers an interrupt if the object is detected and PS Active Force mode. This last mode is used when more conservative power consumption is required, as it allows one reading to be made, before reverting back to the standby mode. When the interrupt event occurs, a flag is set in the status register. To detect a gesture, the Gesture Enable bit has to be set, and the sensor has to be configured to work in the PS Active Force mode. When a trigger bit for the reading is set, all three LEDs will be sequentially triggered. The result will be flagged by the gesture data ready flag and the data can be read from the appropriate register. Also, the interrupt line can be asserted if set so. The provided library offers functions used to read the data and configure the Proximity 5 click in an easy way. The provided example application demonstrates using these functions. It can be used as a reference for a custom design.

Nucleo-64 with STM32F091RC 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

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