This Tiny Sensor Sees in 3D! ToF Sensors w/ STM32, ESP32 & RP2350 Explained (VL53L7CX)

Today I want to show you guys this cool new PCB I made for this sensor here, which is called a multiszone time offlight sensor. Here's what it looks like next to a micro SD card, which is only 11 by 15 mm. It's pretty much just like an ultrasonic sensor if it used infrared light instead, except it's way smaller and allows you to gather up to 64 pixels of distance instead of just one within your field of view. With a much longer range of up to 3.5 meters and millimeter level precision, I'd say it's probably one of the best sensors you could use for 3D scanning, industrial automation, competition robotics, and gesture recognition. Plus, it's not even that expensive. So, in this video, I'll be showing you how these little time offlight sensors offered by ST work, how you can interface with one using an ESP32, RP2350, or STM32, where you can buy one of these little powerhouses for yourself. And lastly, I'll be using the sensor to point a laser straight into my eye because that's just a super original idea. And yeah, I know while I might not be Michael Reeves, I am the same race and I have a monthly upload schedule. So, I'm all you're getting until what, October? Anyways, start the stupid intro. The basic premise to any distance sensor is that a wave of something is sent out and then you time how long it takes for the same wave to be received after an object in its path reflects it back so that you can calculate the distance to that object using known speeds of that wave. That's why it's called a time of flight. For an ultrasonic sensor, it's as easy as sending out a pulse and then listening for it back using PZO elements, which when a voltage is applied to will deform and move the surrounding air, creating sound and vice versa. But for a true infrared timelight sensor, not one of these things, which uses reflectance to approximate distance instead, it's a lot more complicated. First, a laser located on a left here emits light at 940 nm far outside the visible spectrum. Then it'll take anywhere from about 150 picos seconds to 25 nanconds for the light to be reflected from an object and then received back at an array of S pads which are a special type of diode that is reverse biased a few volts above its breakdown voltage to the point where a single photon carries enough energy to trigger an avalanche in which the diode starts to let a lot of current through. A little bit like a TVS when it absorbs a transient. Once this happens, the SPAD is done. it can't detect another photon and continues to let these large currents flow until it's reset by being brought below its breakdown voltage and then back up above again.