Description
This sensor is a carrier/breakout board for ST’s VL53L1X laser-ranging sensor, which offers fast and accurate ranging up to 4 m. It uses the time of flight (ToF) of invisible, eye-safe laser pulses to measure absolute distances independent of ambient lighting conditions and target characteristics like color, shape, and texture (though these things will affect the maximum range). The VL53L1X also features a programmable region of interest (ROI), so the full field of view can be reduced or divided into multiple zones. Distance measurements can be read through a digital I²C interface. The board includes a 2.8 V linear regulator and level-shifters that allow it to work over an input voltage range of 2.6 V to 5.5 V, and the 0.1″ pin spacing makes it easy to use with standard solderless breadboards and 0.1″ perfboards.
Overview
The VL53L1X from ST Microelectronics is a long-distance ranging time-of-flight (TOF) sensor integrated into a compact module. This board is a carrier for the VL53L1X, so we recommend careful reading of the VL53L1X datasheet (1MB pdf) before using this product.
The VL53L1X is effectively a tiny, self-contained lidar system featuring an integrated 940 nm Class 1 laser, which is invisible and eye-safe. Unlike conventional IR sensors that use the intensity of reflected light to estimate the distance to an object, the VL53L1X uses ST’s FlightSense technology to precisely measure how long it takes for emitted pulses of infrared laser light to reach the nearest object and be reflected back to a detector. This approach ensures absolute distance measurements independent of ambient lighting conditions and target characteristics (e.g. color, shape, texture, and reflectivity), though these external conditions do affect the maximum range of the sensor, as do the sensor configuration settings.
Under favorable conditions, such as low ambient light with a high-reflectivity target, the sensor can report distances up to 4 m (13 ft) with 1 mm resolution. See the datasheet for more information on how various external conditions and sensor configurations affect things like maximum range, repeatability, and ranging error. The minimum ranging distance is 4 cm; inside of this range, the sensor will still detect a target, but the measurement will not be accurate. Ranging measurements are available through the sensor’s I²C (TWI) interface, which is also used to configure sensor settings, and the sensor provides two additional pins: a shutdown input and an interrupt output.
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The VL53L1X offers three distance modes: short, medium, and long. Long distance mode allows the longest possible ranging distance of 4 m, but the maximum range is significantly affected by ambient light. Short distance mode is mostly immune to ambient light, but the maximum ranging distance is typically limited to 1.3 m (4.4 ft). The maximum sampling rate in short distance mode is 50 Hz while the maximum sampling rate for medium and long distance modes is 30 Hz. Performance can be improved in all modes by using lower sampling rates and longer timing budgets (as can be seen in the figure above).
For advanced applications, the VL53L1X supports configurable thresholds that can be used to trigger interrupts when a target is detected below a certain distance, beyond a certain distance, outside of a range, or within a range. It also supports an alternate detection mode that generates an interrupt when no target is present. Additionally, unlike its predecessors, the VL53L1X supports a configurable region of interest (ROI) within its full 16×16 sensing array, allowing you to reduce the field of view (FoV). With all 265 detection elements enabled, the FoV is 27°. An “Autonomous Low Power” mode that is specially tuned for advanced presence detection is available. This mode allows for significant system power saving by switching off or waking up the host automatically when a human or object is detected within the configured distance thresholds in the region of interest.
The VL53L1X is a great IC, but its small, leadless, LGA package makes it difficult for the typical student or hobbyist to use. It also operates at a recommended voltage of 2.8 V, which can make interfacing difficult for microcontrollers operating at 3.3 V or 5 V. Our breakout board addresses these issues, making it easier to get started using the sensor, while keeping the overall size as small as possible.
The carrier board includes a low-dropout linear voltage regulator that provides the 2.8 V required by the VL53L1X and allows the sensor to be powered from a 2.6 V to 5.5 V supply. The regulator output is available on the VDD pin and can supply around 100 mA to external devices. The breakout board also includes a circuit that shifts the I²C clock and data lines to the same logic voltage level as the supplied VIN, making it simple to interface the board with 3.3 V or 5 V systems, and the board’s 0.1″ pin spacing makes it easy to use with standard solderless breadboards and 0.1″ perfboards. The board ships fully populated with its SMD components, including the VL53L1X, as shown in the product picture.
