1. Arduino Setup & Flexing the ExBow

2. Installing Software (USB Stick)
Install Arduino
Install Ardublock
duo

3. Blink Program Begin by setting up the circuit as shown to the right
The positive end (long leg) of the LED must be connected to the resistor
The negative end (short leg) of the LED must be connected to ground
Digital Pin 13 (D13)
1000 Ohm Resistor
Long leg
Short leg
LED
Ground

4. Physical Circuit

5. Code
Initialize pin 13 as an output pin - we will output a signal to tell the LED what to do
For us, wherever it says LED_BUILTIN write 13
Turn the LED on
Turn the LED off

6. Completed Code
For us, wherever it says LED_BUILTIN write 13

7. Output
When you’re done, it should look like this

8. Voltage Divider
“A simple circuit which turns a large voltage into a proportionally smaller one”
By changing R1 and R2, we can make Vout be a fraction of Vin
Try R1=1000 Ohms and R2=1000 Ohms
What should you get? What about is R2 is really high?
For the Exbow, R2 will be our “flex” sensor

9. Code

10. Output
To see printed outputs, go to the Arduino Program and click on Tools > Serial Monitor (Text Display) or Serial Plotter (Plot Display)
You should see one constant line
The analog input 0-5V is converted to value

11. Voltage Divider with Flex
arduino---v32/experiment-9-using-a-flex-sensor
Voltage Divider with Flex
Now we integrate the flex sensor into the voltage divider circuit

12. Physical Circuit

13. Code

14. Output Use Serial Plotter
As you move the flex sensor back and forth you should see something to the right

15. Min - Max Function
Range of outputs for person using the flex sensor differs
Use a formula to find bounds
Initiate high minimum and every time the flex sensor has a lower value, the minimum becomes that
Initiate low maximum and every time the flex sensor has a higher value, the maximum becomes that

16. Code

17. Output As the flex value grows, so does the maximum
As the flex value shrinks, so does the minimum
Blue = actual output
red=max
green = min
Label axis

18. Finding the angle
Now that we have the flex values and the range of values, we can convert them to angles
Find the proportional value of the flex from the MAX and MIN and multiply by 180 deg
Example:

19. Code
The left side of the equation maps the Flex value to a value between a new range of 0 to 1 (min to max)
The right side then multiplies that into an angle from 0 to 180

20. Output Use the Serial Monitor: Tools > Serial Monitor
As you move the flex sensor back and forth you should see something to the right
yellow is the angle now

21. Servo Motor Sweep

22. Circuit

23. Code

24. Output Use the Serial Monitor: Tools > Serial Monitor
As the servo moves the arm back and forth you should see something to the right
Try increasing the Max Angle to see how the arm moves

25. Putting it all together