May 20 2020 10 mins 7
This week's EYE on NPI is on a super super fresh NPI that we're excited about - the ST VL53L3CX (https://www.digikey.com/en/product-highlight/s/stmicroelectronics/vl53l3cx-time-of-flight-ranging-sensor) which is the latest version of the 'micro-LIDAR' sensors from ST. Starting with the VL6180X, and continuing to the VL53L0X and VL53L1X, these sensors are really amazing - they have a tiny laser that emits light and is bounced off nearby objects to determine the distance. The sensor has extra-ordinary timing sensing so it can measure the 'time of flight' between the photos emitted by the laser, and when it arrives bounced back. Thus, they are called "Time of Flight / ToF" sensors. VL53L3CX ToF product from STMicroelectronics embeds ST’s third-generation FlightSense patented technology. It combines a high-performance proximity and ranging sensor with multi-target distance measurements and automatic smudge correction. The miniature reflowable package integrates a single-photon avalanche diode (SPAD) array and physical infrared filters to achieve the best ranging performance in various ambient lighting conditions, with a wide range of cover glass windows. There's a lot of ways to measure distance - often folks use IR sensors, these bounce Infrared LED light off an object and measure the amount of light detected. These are really inexpensive and simple to use - you just need an analog reading of the phototransistor voltage, but have a few downsides: the readings are not precise distances, the sensor often have short ranges (usually maxing out at 150cm), and the color and reflectivity of the sensed object affects readings. Darker objects absorb more of the IR so seem to be 'farther', this can cause frustration as seen in this popular video showing different folks trying to use a soap dispenser with IR sensing: lighter skin works, darker skin does not trigger the distance sensor. (https://twitter.com/nke_ise/status/897756900753891328). Ultrasonic is another popular distance measurement, but its slower - relying on sound travel - and is very bulky since you need a transducer. You also can't have anything blocking the transducer. As we mentioned, the VL53L3CX is the latest in this family (https://www.digikey.com/en/product-highlight/s/stmicroelectronics/vl53l3cx-time-of-flight-ranging-sensor) which started with the VL6180X and has grown since. This new chip is the same size and pinout as the previous VL53Lx chips so it should be an easy update. The nifty new capability in this sensor is that it can now track up to 4 objects distances at a time, instead of a single distance. Here are the specs: Long distance and accurate ranging up to 3 m Excellent short distance linearity ST histogram algorithms allow multi-target distance measurement and cover glass crosstalk immunity beyond 80 cm ST algorithms enable dynamic smudge compensation Very small package for easy integration (single module combining laser emitter, SPAD receiving array, and micro-controller in a reflowable package) Can be hidden behind various cover window material and colors (Creative ID) Not affected by target reflectance, material and color, or unlikely traditional IR proximity sensors These chips are super fresh, but you can use our existing EagleCAD design to create your own eval board. (https://github.com/adafruit/Adafruit-VL53L0X-ToF-Distance-Sensor-PCB) There's a reel of chips available at Digi-Key for you to purchase right now! You can find them at part number 497-VL53L3CXV0DH-1CT-ND (https://www.digikey.com/product-detail/en/stmicroelectronics/VL53L3CXV0DH-1/497-VL53L3CXV0DH-1CT-ND/11658314) https://www.digikey.com/
