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Michelle Lab4

Page history last edited by Michelle Lee 12 years, 11 months ago

Part a

part 1
a. Post a copy of your new code in your lab writeup.
int sensorPin = A0; // select the input pin for the potentiometer
int ledPin = 9; // select the pin for the LED
int sensorValue = 0; // variable to store the value coming from the sensor

void setup() {
// declare the ledPin as an OUTPUT:
pinMode(ledPin, OUTPUT);
}

void loop() {
// read the value from the sensor:
sensorValue = analogRead(sensorPin)/4;
// turn the ledPin on
analogWrite(ledPin, sensorValue);

}

part 2

a. Based on the readings from the serial monitor, what is the range of the analog values being read?

0-1023

b. How many bits of resolution does the analog to digital converter (ADC) on the Atmega328 have? How many are you really using with the range of voltages you're seeing?

part 3

a. What resistance do you see with a Multimeter when the sensor is flat? When it is bent?

9 kohm - 33kOhm

b. What kind of voltages should we expect for the Arduino pin based on the sensor resistance?

1.4517 V - 3.9 V

V= IR

At 9 kohms

I=0.0001613 amp

I*9,000 ohms = 1.4517V

at 33 kohms

I=0.0001190 amp

I*33,000=3.9 V

c. How does the range of the LED's brightness change compared to the potentiometer?

It's a lot smaller. The range for potentiometer is 0-1023, whereas the flex sensor has a range from 440-719

Incorporate the LCD or serial monitor into your fading LED/potentiometer code so that you can read out the exact analog value that you are reading in on Analog Pin 0. It's your own lowly multimeter! Change the LED fading code values so that you get the full range of output voltages from using your Flex sensor.

d. Include a copy of your Lowly Multimeter code in your lab write-up.

int sensorPin = A0;    // select the input pin for the potentiometer
int ledPin = 9;      // select the pin for the LED
long sensorValue = 0; // variable to store the value coming from the sensor
long sensorMax = 750;
long sensorMin = 450;

void setup() {
// declare the ledPin as an OUTPUT:
pinMode(ledPin, OUTPUT);
Serial.begin(9600);
}

void loop() {
// read the value from the sensor:
     sensorValue = (((long)analogRead(sensorPin)- sensorMin)*255) /((sensorMax-sensorMin));
     if (sensorValue < 0)
       sensorValue = 0;
     if (sensorValue > 255)
       sensorValue = 255;
     Serial.println(sensorValue);
     delay(10);
// turn the ledPin on
analogWrite(ledPin, sensorValue);
}

part 4

a. What resistance values do you see from your force sensor?

0.5 kOhm

b. Include a copy of your FSR thumb wrestling code in your lab write-up.

void setup() {
// initialize the serial communication:
Serial.begin(9600);
}

void loop() {
// send the value of analog input 0:
String string = analogRead(A0);
string.concat(" vs ");
string.concat(analogRead(A3));
Serial.println(string);
// wait a bit for the analog-to-digital converter
// to stabilize after the last reading:

}
part B

a. Describe the voltage change over sensing range of the sensor.

The voltage at first is low (because the light can't be reflected into the receiver when your hand is too close), then spikes to around 2.7 at around 10cm -15 cm. Then the voltage drops exponentially to the distance.

a. Include your accelerometer read-out code in your write-up.

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