Light Ranger 4 Click is an accurate distance measurement Click board™ based on a ToF (Time of Flight) measurement principle. The FlightSense™ enabled VL53L1X rangefinder module from STMicroelectronics is a complete measurement stack on the chip. It is surprisingly easy to work with, as this highly integrated range finder module exposes only I2C interface, XSH and INT pins to the host controller. It features the invisible Class1 laser emitter, used to emit a narrow band of a harmless modulated light beam in the IR range (940 nm), physical infrared filters and optics to achieve the best ranging performance in various ambient lighting conditions with a range of cover window options. It can measure distances up to 4000mm, with up to 50 Hz ranging frequency.
ToF based light distance meters and rangefinders are one of the most accurate contactless distance measuring devices. The ability to precisely measure distance without making actual contact, allows Light Ranger 4 to be used in industry - for counting dimensions of goods in industry, controlling a safety area, building contactless digital measurement tools. Some other uses for this device could be building 3D visual guidance applications in robotics, for moving it through obstacles, and similar.
Light Ranger 4 Click uses the FlightSense™ enabled VL53L1X rangefinder module from STMicroelectronics. This sensor uses the Class1 laser emitter, which emits light in the range of 940 nm. The light emission is in the IR range of the spectrum and it is not visible by a human eye. It is received by the IR sensor and processed by the integrated sections of the VL53L1X, giving the result on the output register, available via the standard I2C interface. The device is rated as Class 1 LASER product, and it does not cause harmful eye injuries. However, it should not be pointed towards the eyes.
The highly integrated VL53L1X ToF sensor encompasses several integrated sections. It has an embedded MCU, OTP memory, RAM area, ROM area, ranging processing unit and the VCSEL driver. It exposes a simple I2C interface for the communication with the host MCU, offering a range of registers, used for configuring and status reporting. In addition, it offers an interrupt (INT) and XSH (XSHUT) pins routed to the mikroBUS™. Highly configurable interrupt engine allows this pin to be configured to generate interrupt signals for various events, alerting the host MCU about some important status changes, such as the Data Ready event, for example. It can be set to work in both open-drain configurations, as well as in the push-pull mode. Besides the INT pin, XSH pin is also avalible on the Click board™, which can be used for shuting down the main IC. The Click board™ is equipped with the 10K pull-up resistors, so it is advised to configure the INT and XSH pins in open-drain mode.
The measurement is done by comparing the modulation shift of the light in the reflected beam. Therefore, the range and the accuracy depend on the material of the measured object, as well as the photo - pollution of the IR spectrum. The module is designed to suppress the noise and interference, while the programmable Field of view from 15 to 27 degrees allows focused measurement and prevents beam scattering. The measurement is naturally affected by the IR reflectance of an object, so best results are achieved when measuring the distance of the objects that have high IR reflectance. The maximum range that can be measured is 4000mm, while the minimum operational range is 40mm. The measurement error is linear, and it grows with the distance. It stays within 10% of the distance.
Since the VL53L1X ToF sensor module is highly integrated and requires a minimum number of external components to work, this Click board™ has only one SMD jumper (VCC SEL) which can be used to set the power supply voltage between 3.3V and 5V, allowing both 3.3V and 5V tolerant MCUs to be interfaced with the Click board™. The RFD77402 module datasheet offers an extensive information about internal registers and how to configure them. However, the Click comes with the library of functions that provide simplified operation and measurement. The use of these functions is demonstrated in the example, which can be used as the reference for custom design.
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