Second degree equation solver with arduino

This instuctable is about making sort of a calculator that enables the user by using an analog 12-digit keyboard and 4 buttons to input the a,b,c variables into a equation and get the solution for it if there is any.(well if u don't know what an second grade equation is probably u haven't been in high school, even though you can follow this post to learn about microcontrollers.)

It can be a great electronics class project or an microcontroller starter project.  for your own use.

Step 1 Parts list

arduino board....................http://www.oomlout.co.uk/arduino-duemilanove-p-185.html £24.17
medium size breadboard......http://www.oomlout.co.uk/breadboard-830-point-p-250.html £5.11
LCD Display (16 x 2)...........................http://www.oomlout.co.uk/lcd-display-16-x-2-p-212.html £7.15
12 digit keypad...http://cgi.ebay.com/Electric-Keypad-12-Button-Keyboard-24VDC-20mA-Max-/110690838563?pt=LH_DefaultDomain_0&hash=item19c5b02823 .................................$9.99     
4 buttons................................................................................................................$1.00-0 
1 potentiometer.....................................................................................................$1.00-0
16x 500ohm, 4x 1k, 1x 6k resistors .................................................................$2.00-1
3 green LEDs.........................................................................................................$0.25-0
lots of jumpers or striped wires  ........................................................................$1.00-0

And patients!!!!!!  

  tip: if u don't have any of this parts it is highly recommended you buy an arduino starter pack that will include almost every electronic part needed, like potentiometers, wires, leds and maybe an lcd. a good one, which i bought ,is http://www.oomlout.co.uk/starter-kit-for-arduino-ardx-p-183.html

 As for the tools, a soldering iron and a wire striper and cutter should be enough.

Comments

[stratos13pao]

Thank you

i used your library and it worked just fine, it is extremely useful as when i change the power supply (usb /battery) the the values change. it has helped my a ton.

Although i will not update the instructable because i thing the use of libraries is quite more complicated than my suggestion least for a beginner.

thanx again and if u feel like so vote for me

[declanshanaghy]

Nice tutorial.

I think the problem with your keypad reliability is because of contact bounce (also known as switch bounce) (http://en.wikipedia.org/wiki/Switch#Contact_bounce)

I recently updated my analog keypad backpack tutorial to include an Arduino library for use with an analog keypad. It has internal debounce logic so the return values from keypad.readKey() are reliable.

The library also accepts constructor arguments for the resistor values which allows it to calculate the co-responding analog voltage for each key reliably.

Check out step 7. I think it will solve your reliability problems.

L8r,
Dek

P.S.
There is a simpler example of debounce code in
Arduino File Menu -> Examples -> 2.Digital -> Debounce

[aspirine]

really good project!!! i am waiting for the video though.

[MRHint]

Awesome! a quadratic equation solver. That is so cool!