Arduino UNO: Flex Sensor and LEDs

Using the same LED matrix as before, and swapping the Photo Resistor for a Flex (or Bend) sensor, and a slight modification to the code, I can now have a light show that can be controlled by "Bending".

I used my finger to bend the sensor, but I could have attached it to a plant, a tree or anything else that bends. The bending changes the resistance, and therefore the INPUT value at analog pin 0.

The parts required:

• Arduino UNO
• 10 x Red LEDs
• 9 x 330 Ohm resistors for the LEDs
• 1 x 10K Ohm resistors for the flex sensor.
• 1 x Flex sensor
• Wires and Breadboard to connect it all together

Most of the components needed for this project can be sourced from the Sparkfun Inventor's Kit

The video:

The Sketch:

The Arduino Code: 

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/* Flex Sensor and LEDs created by ScottC on 23rd May 2011 updated on 16/05/2012. -----------------------------------------------------*/ //Flex Sensor Pin (flexPin) //the analog pin the Flex Sensor is connected to int flexPin = 0; void setup() { for (int i=4; i<14; i++){ pinMode(i, OUTPUT); //sets the led pins 4 to 13 to output } } void loop(){ //Ensure to turn off ALL LEDs before continuing for (int i=4; i<14; i++){ digitalWrite(i, LOW); } /* Read the flex Level Adjust the value 130 to 275 to span 4 to 13 The values 130 and 275 may need to be widened to suit the minimum and maximum flex levels being read by the Analog pin */ int flexReading = map(analogRead(flexPin), 130, 275, 4, 13); // Make sure the value does not go beyond 4 or 13 int LEDnum = constrain(flexReading, 4, 13); /*Call the blink function: this will turn the LED on for 10 milliseconds, and keep it off for only 1 millisecond. You can change the blink rate by changing these values, however, I want a quick response time when the flex sensor bends, hence the small values. LEDnum determines which LED gets turned on.*/ blink(LEDnum, 10,1); } // The blink function - used to turn the LEDs on and off void blink(int LEDPin, int onTime, int offTime){ // Turn the LED on digitalWrite(LEDPin, HIGH); // Delay so that you can see the LED go On. delay(onTime); // Turn the LED Off digitalWrite(LEDPin, LOW); // Increase this Delay if you want to see an actual blinking effect. delay(offTime); }

The flex sensor pins/legs are a bit fragile, so be careful when poking it into the breadboard.

For more projects - have a look at the ArduinoBasics Project Page