Sensors and sensing

electrical signaldigital signal

LEGO sensors

RCX sensors

NXT sensors

RJ12 connector

6 wire cable

2 wire cable

2x2 plate connector

stimuli

sensor control program

AD sensors

TemperatureSoundLight

I2C sensors

Ultrasonic

analog quantity,e.g. light

digital quantity,e.g. light %

interface

I2C

AD converter

Step 1

Step 2

RCX input port RCX touch sensor

V(off) = 5 V V(on) = 5 *500/(500+10000) V = 0.24 V

V(through R) = 5*R/(R+10000)Raw Value(R) = 1023 * R/(R+10000)

Raw Value(500) = 1023 * 500/(500+10000) = 49Raw Value(inf) = 1023 * inf/(inf+10000) = 1023

10 000 ohm

R ohm

5 V

0 V

Voltage divider

Passive sensors touch, temperature

Active sensors light, rotation

Passive sensors touch, temperature

Active sensors light, rotation

Raw Value(R) = 1023 * R/(R+10000) ohm

10 000 ohm

R ohm

5 V

0 V

Signal-to-symbol

stimuli

sensor control program interface

raw valueresistance

raw valuetemperature

raw valueon/off

raw valueclap

raw valueblack/white

time of flightdistance

(57,28)

(27,24)

Measured Distance =

23/cos(30) ~ 27 cm 23 cm

Ialt 57 grader2730

Embedded Java

The leJOS API classes provide access to thehardware. Especially the sensor ports and sensors:

TouchSensor

LightSensor

UltrasonicSensor

SensorPort

Interpret raw sensor value as pressed/released

Lesson 1, Line follower

Lesson 2, Tracker and Wall follower

AD sensors

TemperatureSoundLight

I2C sensors

UltrasonicCompassAccelerometerRFIDGPS

AD sensors

TemperatureSoundLight

I2C sensors

UltrasonicCompassAccelerometerRFIDGPS

Lesson 2, Tracker and Wall follower