Step 4: Built the Circuit
Now lets move on to controlling the seven segment display with the arduino.
The circuit is pretty straight forward connect the common cathode's to gnd with a 330 ohm current limiting resistor. Connect the seven segment displays pin number 7(A) to arduino pin2 , 6(B) to arduino pin3 , 4 (C) to arduino pin 4 , 2 (D) to arduino pin5 , 1 (E) to arduino pin6 , 9 (F) to arduino pin7 , 10 (G) to arduino pin8 , 5 (DP) to arduino pin9.For the 2nd project first make the multiplexing circuit below and then follow these connections pattern.Segment A to pin 7, Segment B to pin 8, Segment C to pin 4, Segment D to pin 3, Segment E to pin 2, Segment F to pin 6, Segment G to pin 5, Gnd1 via resistor to pin 11, Gnd2 via resistor to pin 9.
I have also included the fritzing digram(The worst you can get as I am not good at making circuit diagrams) for the multiplexed circuit and the simple circuit and pinout of the seven segment display .