Laboratorio 9 de Sensores

Universidad Nacional Mayor de San Marcos

Facultad de Ingeniería de Sistemas e Informática

Arquitectura de Computadoras

Laboratorio 9 – Sensores

I. Sensor de sonido analógico

This small breakout board couples a small electret microphone with a 100x opamp to amplify the sounds of voice, door knocks, etc loud enough to be picked up by a microcontroller's Analog to Digital converter.

Pin Definition

The definition of sound sensor pin is

1. Signal Output 2. GND 3. Power

El código es:

void setup() { Serial.begin(9600); // open serial port, set the baud rate to 9600 bps } void loop() { int val; val=analogRead(0); //connect mic sensor to Analog 0 Serial.println(val,DEC);//print the sound value to serial delay(300); }

II. Sensor de movimiento infrarrojo digital

This is a simple to use motion sensor. Power it up and wait 1-2 seconds for the sensor to get a snapshot of the still room. If anything moves after that period, the 'alarm' pin will go low.

Specification

§ Type: Digital § Supply Voltage:3～5V § Current:50µA § Working temperature:0℃～＋70℃ § Output level(HIGH):4V § Output level(LOW):0.4V § Detect angle:110 Degree § Detect distance:7 meters § Size:28mm×36mm § Weight:25g Pin Definition

§ +:Power 5V § -:GND § OUT:Digital Signal Out

For DFRobot Version

§ 1:Digital Signal Out § 2:VCC (5V) § 3:GND

El código de uso es:

/* plug infrared motion sensor on digital port 3. If signal is detected, digitalRead will be high. Switch the resistor backward to adjust the sensitivity as you want. */ void setup() { Serial.begin(9600); } void loop() { Serial.println(digitalRead(3)); delay(100); }

III. Distance Measuring Sensor Unit

The Sharp distance sensors are a popular choice for many projects that require accurate distance measurements. This IR sensor is more economical than sonar rangefinders, yet it provides much better performance than other IR alternatives. Interfacing to most microcontrollers is straightforward: the single analog output can be connected to an analog-to-digital converter for taking distance measurements, or the output can be connected to a comparator for threshold detection. The detection range of this version is approximately 10 cm to 80 cm (4" to 32"); a plot of distance versus output voltage is shown below.

The GP2Y0A21 uses a 3-pin JST connector that connects to our 3-pin JST cable for Sharp distance sensors (not included) as shown in the upper picture on the right. It is also simple to solder three wires to the sensor where the connector pins are mounted (see the lower picture to the right). When looking at the back, the three connections from left to right are power, ground, and the output signal.

NOTE: All Sharp sensors from DFRobot are shipped with JST cable.

Specification

· operating voltage: 4.5 V to 5.5 V · average current consumption: 30 mA (typical) · distance measuring range: 10 cm to 80 cm (4" to 32") · output type: analog voltage · output voltage differential over distance range: 1.9 V (typical) · response time: 38 ± 10 ms · package size: 29.5×13.0×13.5 mm (1.16×0.5×0.53") · weight: 3.5 g (0.12 oz)

El código seria :

int IRpin = 1; // analog pin for reading the IR sensor void setup() { Serial.begin(9600); // start the serial port } void loop() { float volts = analogRead(IRpin)*0.0048828125; // value from sensor * (5/1024) - if running 3.3.volts then change 5 to 3.3 float distance = 65*pow(volts, -1.10); // worked out from graph 65 = theretical distance / (1/Volts)S - luckylarry.co.uk Serial.println(distance); // print the distance delay(100); // arbitary wait time. }

Looking at our graph above from the datasheet, this converted value is of no use to us so we need to convert this value back to the true analog value. How? We take the voltage rating of the power supply and divide by 1024 to give us a value per step. So for instance:

5v/1024 = 0.0048828125

We take this value and multiply by what the sensor sends back to get our voltage reading. The next stage is to work out an equation from the graph on the data sheet to get the theoretical distance from the voltage reading, if we look at the graph between 20 and 150cm you can see that its exponential.

To get our distance on the graph I came up with:

1/Volts * 65

I got 65 by taking the distance on the graph and dividing that by 1/Volts. So now we know what to multiply our voltage results by to get the distance. This is fine if we just had one value to read or if this was a linear graph, in that the change in voltage was always the same amount of distance.

For the exponential change we have to turn our value now into an exponent, a fancy way of saying x to the power of y. So our formula for distance from voltage reading is now something like:

distance = (Volts x)*65.

Since our graph is a decaying exponential the value of x will be a fraction – to write this as a exponent we have to use a minus number e.g. -1. The exponent -1 is the equivalent of the fraction 1/2 which is 0.5 as a decimal.

Now through trial and error I programmed this into my Arduino and changed the exponent until my readings became accurate(ish) I started at -1 and by co-incidence the next value I tried was -1.1 which is 11/10 as a fraction, 0.65 as a decimal and oddly enough 1/100th of my distance ration, 65!

IV. Termistores

The DFRobot LM35 Linear Temperature Sensor is based on the semiconductor LM35 temperature sensor. The DFRobot LM35 Linear Temperature Sensor can be used to detect ambient air temperature. This sensor is produced by National Semiconductor Corporation and offers a functional range between -40 degree Celsius to 150 degree Celsius. Sensitivity is 10mV per degree Celsius. The output voltage is proportional to the temperature.

Pin Definition

The definition of gray-scale sensor pin is

1. Signal Output 2. GND 3. Power

Codigo utilizado para la prueba:

void setup() { Serial.begin(9600);//Set Baud Rate to 9600 bps } void loop() { int val; int dat; val=analogRead(0);//Connect LM35 on Analog 0 dat=(500*val)>>10; Serial.print("Tep:"); //Display the temperature on Serial monitor

Serial.print(dat); Serial.println("C"); delay(500); }

La salida generada es:

Control de Motor por temperatura

En el caso del motor eléctrico, este se conecta en GND y el otro pin a la línea 10 digital.

El código para su funcionamiento es:

int led=5;

int ntc=0;

int motor=10;

int medida=0;

int nivel=59; //variable que guarda el límite de temperatura al que se activa el ventilador valor anterior 700

void setup(){

pinMode(led,OUTPUT);

pinMode(motor,OUTPUT);

Serial.begin(9600);

}

void monitoriza(){ //procedimiento que envía al puerto serie, para ser leído en el monitor,

Serial.print("La medida es ...");

Serial.println(medida);

//Serial.print();

delay(1000); //para evitar saturar el puerto serie

}

void loop(){

medida=analogRead(ntc);

monitoriza();

if(medida>nivel){ //si la señal del sensor supera el nivel marcado:

digitalWrite(led,HIGH); //se enciende un aviso luminoso

digitalWrite(motor,HIGH); //arranca el motor

}

else{ // si la señal está por debajo del nivel marcado

digitalWrite(led,LOW);

digitalWrite(motor,LOW); // el motor se para

}

}

V. Uso de Relays

El Relé es un dispositivo, que funciona como un interruptor controlado por un circuito eléctrico en el que, por medio de un electroimán, se acciona un juego de uno o varios contactos que permiten abrir o cerrar otros circuitos eléctricos independientes.

De esta forma, podremos separar dos circuitos que funcionen con voltajes diferentes. Uno a 5V (Arduino) y otro a 220V (la bombilla). Para este ejemplo, se utilizara un circuito de 220V con un máximo de 10A.

Conmutación entre leds

Diagrama esquemático

Codigo:

int ledPin = 2; // *********** CHANGE TO PIN 2 ************ void setup() // run once, when the sketch starts { pinMode(ledPin, OUTPUT); // sets the digital pin as output } void loop() // run over and over again { digitalWrite(ledPin, HIGH); // sets the LED on delay(1000); // waits for a second digitalWrite(ledPin, LOW); // sets the LED off delay(1000); // waits for a second }

Encendido de foco de luz El diagrama esquemático para este circuito seria:

El código para este circuito seria:

int relayPin = 8; // PIN al que va conectado el relé void setup(){ pinMode(relayPin, OUTPUT); } void loop() { digitalWrite(relayPin, HIGH); // ENCENDIDO delay(2000); digitalWrite(relayPin, LOW); // APAGADO delay(2000); } Encendido de foco por LDR y Relay

Se utilizara el siguiente circuito:

Para este control de foco por LDR se esta considerando lo siguiente:

1. Un pin del LDR va a ingresar a la entrada A0.

2. La salida del transistor que es parte del control del relay ira al pin D8.

El código correspondiente será:

int relayPin = 8; // PIN al que va conectado el relé

int lightPin = 0; //the analog pin the LDR is connected to

void setup(){

pinMode(relayPin, OUTPUT);

Serial.begin(9600);

}

void loop() {

int threshold = 300;

int valor= analogRead(lightPin);

Serial.println(valor);

if(valor < threshold){

digitalWrite(relayPin, HIGH); // ENCENDIDO

}else{

digitalWrite(relayPin, LOW); // APAGADO

}

}

Sensor de Temperatura y de Distancia

Codigo para el TMP36 solo:

const unsigned int BAUD_RATE = 9600;

const unsigned int TEMP_SENSOR_PIN = 0;

const float SUPPLY_VOLTAGE = 5.0;

void setup(){

Serial.begin(BAUD_RATE);

}

void loop(){

Serial.print(get_temperature());

Serial.println(" C");

delay(1000);

}

const float get_temperature(){

const int sensor_voltage = analogRead(TEMP_SENSOR_PIN);

const float voltage = sensor_voltage * SUPPLY_VOLTAGE / 1024;

return (voltage * 1000 - 500) / 10;

b. Los dos sensores juntos:

const unsigned int TEMP_SENSOR_PIN = 0;

const float SUPPLY_VOLTAGE = 5.0;

const unsigned int PING_SENSOR_IO_PIN = 7;

const float SENSOR_GAP = 0.2;

const unsigned int BAUD_RATE = 9600;

float current_temperature = 0.0;

unsigned long last_measurement = millis();

void setup() {

// put your setup code here, to run once:

Serial.begin(BAUD_RATE);

}

void loop() {

// put your main code here, to run repeatedly:

unsigned long current_millis = millis();

if (abs(current_millis - last_measurement) >= 1000){

current_temperature = get_temperature();

last_measurement = current_millis;

}

Serial.print(scaled_value(current_temperature));

Serial.print(",");

const unsigned long duration = measure_distance();

Serial.println(scaled_value(microseconds_to_cm(duration)));

delay(100);

}

long scaled_value(const float value){

float round_offset = value < 0 ? -0.5 : 0.5;

return (long)(value * 100 + round_offset);

}

const float get_temperature(){

const int sensor_voltage = analogRead(TEMP_SENSOR_PIN);

const float voltage = sensor_voltage * SUPPLY_VOLTAGE / 1024;

return (voltage * 1000 - 500) / 10;

}

const float microseconds_per_cm(){

return 1 / ((331.5 + (0.6 * current_temperature)) / 10000);

}

const float sensor_offset(){

return SENSOR_GAP * microseconds_per_cm() * 2;

}

const float microseconds_to_cm(const unsigned long microseconds){

const float net_distance = max(0, microseconds - sensor_offset());

return net_distance / microseconds_per_cm() / 2;

}

const unsigned long measure_distance(){

pinMode(PING_SENSOR_IO_PIN, OUTPUT);

digitalWrite(PING_SENSOR_IO_PIN, LOW);

delayMicroseconds(2);

digitalWrite(PING_SENSOR_IO_PIN, HIGH);

delayMicroseconds(5);

digitalWrite(PING_SENSOR_IO_PIN, LOW);

pinMode(PING_SENSOR_IO_PIN, INPUT);

return pulseIn(PING_SENSOR_IO_PIN, HIGH);

}

Acelerometro

Se usara el acelerómetro del Kit, DFRobot Triple Axis Accelerometer MMA7361

Introduction

The MMA7361 from Freescale is a very nice sensor with easy analog interface. The MMA7361 is a 3.3V part and outputs an analog voltage for each of the three outputs. This voltage is in ratio to the measured acceleration and to the supply voltage (ratiometric). It has selectable sensitivity by dip switch. You will need some extra hardware to convert this analog signal to a usable digital one. The Arduino is really good option for it. This break board is especially designed for Arduino which has 3 JST connector that can be easily plug into our IO/Sensor expansion board.

Specification

· Voltage:3.3-8V · Selectable sensitivity:±1．5g/6g · Low power:500µA @ measurement mode，3µA @standby ； · High sensivity: 800 mV/g @ 1.5g； · Interface:Analog Output · Low pass filter · Size:23x26mm · Weight: 5 gram

Programa de prueba: const unsigned int X_AXIS_PIN = 2; const unsigned int Y_AXIS_PIN = 1;

const unsigned int Z_AXIS_PIN = 0; const unsigned int BAUD_RATE = 9600; int min_x, min_y, min_z; int max_x, max_y, max_z; void setup() { // put your setup code here, to run once: Serial.begin(BAUD_RATE); min_x = min_y = min_z = 1000; max_x = max_y = max_z = -1000; } void loop() { // put your main code here, to run repeatedly: const int x = analogRead(X_AXIS_PIN); const int y = analogRead(Y_AXIS_PIN); const int z = analogRead(Z_AXIS_PIN); min_x = min(x, min_x); max_x = max(x, max_x); min_y = min(y, min_y); max_y = max(y, max_y); min_z = min(z, min_z); max_z = max(z, max_z); Serial.print("x("); Serial.print(min_x); Serial.print("/"); Serial.print(max_x); Serial.print("), y("); Serial.print(min_y); Serial.print("/"); Serial.print(max_y); Serial.print("), z("); Serial.print(min_z); Serial.print("/"); Serial.print(max_z); Serial.println(")"); }

Otro ejemplo de uso seria: const unsigned int X_AXIS_PIN = 2; const unsigned int Y_AXIS_PIN = 1; const unsigned int Z_AXIS_PIN = 0; const unsigned int NUM_AXES = 3; const unsigned int PINS[NUM_AXES] ={ X_AXIS_PIN, Y_AXIS_PIN, Z_AXIS_PIN }; const unsigned int BUFFER_SIZE = 16; const unsigned int BAUD_RATE = 9600; int buffer[NUM_AXES][BUFFER_SIZE]; int buffer_pos[NUM_AXES] = { 0 }; int get_axis(const int axis){

delay(1); buffer[axis][buffer_pos[axis]] = analogRead(PINS[axis]); buffer_pos[axis] = (buffer_pos[axis] + 1) % BUFFER_SIZE; long sum = 0; for (int i = 0; i < BUFFER_SIZE; i++) sum += buffer[axis][i]; return round(sum / BUFFER_SIZE); } int get_x() { return get_axis(0);} int get_y() { return get_axis(1);} int get_z() { return get_axis(2);} void setup() { // put your setup code here, to run once: Serial.begin(BAUD_RATE); } void loop() { // put your main code here, to run repeatedly: Serial.print(get_x()); Serial.print(" "); Serial.print(get_y()); Serial.print(" "); Serial.println(get_z()); }

Implementando para control de juego:

Sensor de Humedad (Moisture Sensor)

This moisture sensor can read the amount of moisture present in the soil surrounding it. It's a low tech sensor, but ideal for monitoring an urban garden, or your pet plant's water level. This is a must have tool for a connected garden! This sensor uses the two probes to pass current through the soil, and then it reads that resistance to get the moisture level. More water makes the soil conduct electricity more easily (less resistance), while dry soil conducts electricity poorly (more resistance).

It will be helpful to remind you to water your indoor plants or to monitor the soil moisture in your garden.

Specification

Power supply: 3.3v or 5v Output voltage signal: 0~4.2v Current: 35mA Pin definition: 1-Analog output(Blue wire) 2-GND(Black wire) 3-Power(Red wire) Size: 60x20x5mm Value range:

1. 0 ~300 : dry soil 2. 300~700 : humid soil 3. 700~950 : in water

Shipping List

Moisture sensor(1 unit) Analog Sensor Cable (1 unit)

Connection Diagram

Ejemplo

/* # Example code for the moisture sensor # Editor : Lauren # Date : 13.01.2012 # Version : 1.0 # Connect the sensor to the A0(Analog 0) pin on the Arduino board # the sensor value description

# 0 ~300 dry soil # 300~700 humid soil # 700~950 in water */ void setup(){ Serial.begin(57600); } void loop(){ Serial.print("Moisture Sensor Value:"); Serial.println(analogRead(0)); delay(100); }

Sensor de gas analógico (Analog Alcohol Sensor)

The analog gas sensor - MQ3 is suitable for detecting alcohol, this sensor can be used in a Breathalyser.It has a high sensitivity to alcohol and small sensitivity to Benzine. The sensitivity can be adjusted by the potentiometer. Specification

· Power supply needs: 5V · Interface type: Analog · Pin Definition: 1-Output 2-GND 3-VCC · High sensitivity to alcohol and small sensitivity to Benzine · Fast response and High sensitivity · Stable and long life · Simple drive circuit · Size: 40x20mm

Pin Definition

1. Signal Output 2. GND 3. Power

Circuito implementado

Sample Code

///Arduino Sample Code

void setup()

{

Serial.begin(9600); //Set serial baud rate to 9600 bps

}

void loop()

{

int val;

val=analogRead(0);Read Gas value from analog 0

Serial.println(val,DEC);//Print the value to serial port

delay(100);

}