Ultrasonic distance sensors work in the same way that sonar works. A high-pitched pulse of sound is sent out, it echoes off nearby objects, and the sensor listens for its return. The longer the time between pulse and echo, the further away the object is. The common HC-SR04 sensor is widely available, and often costs just a pound or two. (Ed: Under $5 US)
The code to read the sensor in CircuitPython is easy:
from adafruit_hcsr04 import HCSR04
sonar = HCSR04(board.D2, board.D3)
Eink, E-paper, Think Ink – Collin shares six segments pondering the unusual low-power display technology that somehow still seems a bit sci-fi – http://adafruit.com/thinkink
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.