[HW] 2015 – sensors purpose of a sensor: convert a state or change in the physical world into an electrical signal

some sensible phenomena light – smoke – sound frequency – sound level – color – flow – identity – proximity – bending – movement – position – distance – conductance – temperature – tilt – vibration – direction – gravity – heartbeat – voltage – taste – speed – magnetic field – rotation – time elapsed – current – acceleration – fluid level – touch – force – gas presence – humidity – barometric pressure – air pressure – proximity – gesture – capacity – angle – presence – orientation – balance – air pressure http://en.wikipedia.org/wiki/List_of_sensors

operating principles electromechanical on/off or rotary switch reed relay bi-metal resistive temperature (ntc, ptc) light (LDR) pressure / force (FSR) angle (potentiometer) fluid level inductive rotation ac current sound (dynamic microphone)

operating principles (2) optical infrared (passive = object radiation / active = beam) IR sensor light barrier – laser - lamp/LED - photodiode distance – US, IR camera, kinect light (intensity, color) capacitive moist distance / proximity acceleration hall effect magnetic field, movement, distance compass, orientation electromechanical pressure flow

how to read the sensor: communication simple interfaces discrete voltage (on/off) analog: voltage level that reflects the physical situation time – duration – frequency capacity (charge time, frequency) resistance more complex: use a protocol asynchronous serial (RS232, RS485, USB, MIDI) clocked serial (e.g. SPI) I2C 1wire CAN

sensor behaviour: static or dynamic dynamic: reacts to a change in the situation only static: continuously reflects the actual situation to adapt or to be actual detecting people in a room: - infrared (burglar alarm) - camera + background substraction

movement: toggle, rocker- or slide switch

momentary /touch button

micro switch – well defined switching point reed switch – requires no physical contact

angular movement: potentiometer

infrared: light barrier

passive infrared (pir) http://actionsensorhack.weebly.com/

radar

acceleration / gravitation

angular movement: gyroscope, compass

pressure: force sensitive resistor (FSR)

pressure: flex sensor

distance - ultrasonic

using a cheap ultrasound sensor

Fritzing example Arduino code smoothing with Puredata

distance: infrared (angle)

Sharp GP2Y0A21 output voltage / distance

distance: capacitative (proximity)

touch: capacitative Arduino/Processing: ‘touché’ http://arduino.cc/blog/2012/06/01/touche-with-arduino/ arduino theremin arduino cap sensor

touch key sensor: Atmel QT1010

temperature: bimetal switch

temperature: resistor, PTC

light dependent resistor (LDR) photo transistor light dependent resistor (LDR)

LDR

color Taos TCS230 / TCS3200

color Adafruit Flora Color Sensor w. TCS34725 3.3V (!?) I2C interface

color

sound: electret microphone mic output level: max 1 mV arduino input level: 5 V = 5000 mV

sound: connecting audio to Arduino line level (-2.5..2.5V) microphone level (0.5mV AC)

sound: piezo element