Introduction

In this example, you are learning how to use a proximity sensor. This sensor (TCRT5000) uses reflection as a surface theory to work. A white and polished surface reflects a large percentage of light and a black and rough surface absorbs (not reflect) a large percentage of light that incidence on the surface.

Learning outcomes:

• Reflection theory using Infrared radiations.
• Turning physical parameters to an analog electric signal.

Theory

A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal.

Features:

• Supply voltage 3.3V ~ 5V
• Detect distance 1 mm ~ 8 mm

Methodology

1. As the first step, you should connect a Magicbit proximity sensor to the Magicbit core board. For this, you can use one side connector from four-side connectors of the Magicbit core board or if you want to extend the length of the connection you can use jumper wires.
2. For this example, the proximity sensor was connected to the upper left connector of the Magicbit core board.
3. Then connect the Magicbit to your pc and upload the code. You can get outputs using a serial monitor.

Code

from machine import Pin, ADC
from time import sleep

prox = ADC(Pin(34))
prox.atten(ADC.ATTN_11DB)       #Full range: 3.3v

while True:
   prox_value = prox.read()
   print(prox_value)
   sleep(0.1)