ProjectAbout

Digital Stop Watch

Digital Logic & Design

Presented by1. M. Asad ali1. M. Habib ajmal2. M. khurram shahzad

Presented To

Ma’am Noor Ul Ain

MCS-1

Components used in the the Project

• J-K Flip Flop• Switch • Power• Alternator• 7-Segment Display Coded Decimal (BCD)

Display

• Flip Flop: The memory elements in a sequential circuit are called flip-flops. A flip-flop circuit has two outputs, one for the normal value and one for the complement value of the stored bit. Binary information can enter a flip-flop in a variety of ways and gives rise to different types of flip-flops. a flip-flop or latch is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are a fundamental building block of digital electronics systems used in computers, communications, and many other types of systems.

1. JK Flip Flop:• JK flip Flop is the most widely used of all the

flip-flop designs and is considered to be a universal flip-flop circuit. The sequential operation of the JK flip flop is exactly the same as for the previous SR flip-flop with the same “Set” and “Reset” inputs. The difference this time is that the “JK flip flop” has no invalid or forbidden input states of the SR Latch.

Symbol

• The JK flip flop is basically a gated SR-FlipFlop with the addition of a clock input circuitry that prevents the illegal or invalid output condition that can occur when both inputs S and R are equal to logic level “1″. Due to this additional clocked input, a JK flip-flop has four possible input combinations, “logic 1″, “logic 0″, “no change” and “toggle”. The symbol for a JK flip flop is similar to that of an SR Bistable Latch.

• Both the S and the R inputs of the SR bistable are replaced by two inputs called the J and K inputs, respectively.

• Table for Flip Flop:

Truth Table for 3-Bits Input

Present State Next State J-K Flip Flop I/P

I0 I1 I2

0 0 0

0 0 1

0 1 0

0 1 1

1 0 0

1 0 1

1 1 0

1 1 1

I0 I1 I2

0 0 1

0 1 0

0 1 1

1 0 0

1 0 1

1 1 0

1 1 1

J K

1 1

1 1

1 1

1 1

1 1

1 1

1 1

1 1

Implementation

Static State

Working State

MRHabibi