Flex Sensor

Flex sensorn är en variabel resistor det blir mer resistans desto mer man böjer sensorn. När den inte är böjd så är det en 30kΩ resistor, men om man böjer den till 90 grader så ökar det till 70kΩ. En flex sensor har använts i Nintendo Power Glove, men man kan även använda den till en dörrsensor.

Här är kod som man kan använda till en Flex Sensor:

/
Flex_Sensor_Example.ino
Example sketch for SparkFun’s flex sensors
(https://www.sparkfun.com/products/10264)
Jim Lindblom @ SparkFun Electronics
April 28, 2016
Create a voltage divider circuit combining a flex sensor with a 47k resistor.
•	The resistor should connect from A0 to GND.
•	The flex sensor should connect from A0 to 3.3V
As the resistance of the flex sensor increases (meaning it’s being bent), the
voltage at A0 should decrease.
Development environment specifics:
Arduino 1.6.7
/
const int FLEX_PIN = A0; // Pin connected to voltage divider output
// Measure the voltage at 5V and the actual resistance of your
// 47k resistor, and enter them below:
const float VCC = 4.98; // Measured voltage of Ardunio 5V line
const float R_DIV = 47500.0; // Measured resistance of 3.3k resistor
// Upload the code, then try to adjust these values to more
// accurately calculate bend degree.
const float STRAIGHT_RESISTANCE = 37300.0; // resistance when straight
const float BEND_RESISTANCE = 90000.0; // resistance at 90 deg
void setup()
{
Serial.begin(9600);
pinMode(FLEX_PIN, INPUT);
}
void loop()
{
// Read the ADC, and calculate voltage and resistance from it
int flexADC = analogRead(FLEX_PIN);
float flexV = flexADC * VCC / 1023.0;
float flexR = R_DIV * (VCC / flexV – 1.0);
Serial.println(“Resistance: ” + String(flexR) + ” ohms”);
// Use the calculated resistance to estimate the sensor’s
// bend angle:
float angle = map(flexR, STRAIGHT_RESISTANCE, BEND_RESISTANCE,
0, 90.0);
Serial.println(“Bend: ” + String(angle) + ” degrees”);
Serial.println();
delay(500);
}

Källor:
https://learn.sparkfun.com/tutorials/flex-sensor-hookup-guide/all