I want to show you in this "Instructable" how to control 7-Segment-Display

What you need:
*Arduino Duemilanove
*a lot of 7-Segment-Display
*a lot of push Button
*a potentiometer
*8 x 120 Ohm resistor
*4 x 1k2 Ohm resistor
*2 x 1k Ohm resistor
*4 x BC547 Transistor
*1 x 74HC595
*breadboard
*wire

Step 1: 7-Segment Displaying With Potentiometer

On this step i worked with a shiftregister (74HC595). I connected the pins of 7-Segment to the shiftregister(a-g -> Q0, Q6). And a potentiometer to displaying the characters. Down here you can see the schematic.

latchPin = 8; // pin 12 on the 74hc595
clockPin = 12; // pin 11 on the 74hc595
dataPin = 11; // pin 14 on the 74hc595

And you can download the Programm Code

7SegmentShiftregister.txt
Download

Step 2: Count Down and Up With 2 Buttons

This step is about controlling the display with 2 push buttons to count up and down. The schematic that you can see down here is very simple. I have connected the Segment Pins (A to G) in Arduino (Pin 2 to 8) and the reading buttons happens through Arduino Pin 13 (countup) and Pin 12 (countdown).
I used the debouncer library to read the switched button successfully...

DONT FORGET THE RESISTORS