Pin Details of Digital Logic Gates:

Transcription

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3 Pin Details of Digital Logic Gates: (3)

4 Postulates and Theorems of Boolean algebra: S. No Postulate/Theorem Duality Remarks 1. X + 0 = X X.1 = X - 2. X + X = 1 X.X = 0-3. X + X = X X.X = X - 4. X + 1 = 1 X.0 = 0-5. (X ) = X - Involution 6. X + Y = Y + X X.Y = Y.X Commutative 7. X + (Y + Z) = (X + Y) + Z X.(Y.Z) = (X.Y).Z Associative 8. X.(Y + Z) = X.Y + X.Z X + (Y.Z) = (X + Y)(X + Z) Distributive 9. (X + Y) = X Y (XY) = X + Y DeMorgan s Theorem 10. X + XY = X X.(X + Y) = X Absorption Bit Grouping: Bit - A single, bivalent unit of binary. Equivalent to a decimal "digit." Crumb, Tydbit, or Tayste - Two bits. Nibble or Nybble - Four bits. Nickle - Five bits. Byte - Eight bits. Deckle - Ten bits. Playte - Sixteen bits. Dynner - Thirty-two bits. Word - (system dependent). Arithmetic Notations: Augend + Addend = Sum Minuend Subtrahend = Difference Multiplicand X Multiplier = Product Dividend / Divisor = Quotient (4)

5 Verification of Logic Gates: (5)

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8 EXP. NO : 1 DATE : VERIFICATION OF BOOLEAN THEOREMS USING DIGITAL LOGIC GATES Aim: To verify the truth table of basic Boolean algebric laws by using logic gates. Components Required: S.NO COMPONENTS RANGE QUANTITY 1 Digital IC trainer kit IC Bread board Connecting wires - As required Theory: Demorgan s Theorems First Theorem: It states that the complement of a product is equal to the sum of the complements. (AB) =A +B Second Theorem: It states that the complement of a sum is equal to the product of the complements. (A+B) =A.B Boolean Laws: Boolean algebra is a mathematical system consisting of a set of two or more distinct elements, two binary operators denoted by the symbols (+) and (.) and one unary operator denoted by the symbol either bar (-) or prime ( ). They satisfy the commutative, associative, distributive and absorption properties of the Boolean algebra. Commutative Property: Boolean addition is commutative, given by A+B=B+A Boolean algebra is also commutative over multiplication, given by A.B=B.A (8)

9 De-Morgan s Theorem: 1 De-Morgan s Theorem: 2 (9)

10 Associative Property: The associative property of addition is given by A+ (B+C) = (A+B) +C The associative law of multiplication is given by A. (B.C) = (A.B).C Distributive Property: The Boolean addition is distributive over Boolean multiplication, given by A+BC = (A+B) (A+C) Boolean multiplication is also distributive over Boolean addition given by A. (B+C) = A.B+A.C Realization of circuits for Boolean expression after simplification: A binary variable can take the value of 0 or 1. A Boolean function is an expression formed with binary operator OR, AND and a unary operator NOT, parenthesis function can be 0 or 1. For example, consider the function The prime implicants are found by using the elimination of complementary function. The circuit diagram for the function is drawn using AND.OR and NOT gates. The output for the corresponding input of A 1, A 0, B 1, B O is calculated and the truth table is drawn. Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. (10)

11 Commutative Law: Truth Table: Input Output A B A+B B+A Associative Law: Truth Table: Input Output A B C A+B (A+B)+C B+C A+(B+C) (11)

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13 Distributive Law: Truth Table: Input Output A B C B+C A.(B+C) A.B A.C A.B+A.C (13)

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16 Description Max. Marks Marks Secured Preparation 30 Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: performed. Thus the verification of Boolean laws and theorems using digital logic gates were (16)

17 Truth Table for Arbitrary Function: Input Output A 1 A 0 B 1 B 0 F Realization of simplified Boolean expression using K-Map: (17)

18 EXP. NO : 2 DATE : DESIGN AND IMPLEMENTATION OF COMBINATIONAL CIRCUITS USING BASIC GATES FOR ARBITRARY FUNCTIONS AND CODE CONVERTERS Aim: To design and implement a combinational circuit to convert gray code to Binary and BCD to Excess-3 vice versa. Components Required: S.NO COMPONENTS RANGE QUANTITY 1 Digital IC Trainer kit IC Connecting wires - As required 4 Bread board - 1 Theory: Binary to Gray Vice versa: The binary coded decimal (BCD) code is one of the early computer codes. Each decimal digit is independently converted to a 4 bit binary number. A binary code will have some unassigned bit combinations if the number of elements in the set is not a multiple power of 2. The 10 decimal digits form such a set. A binary code that distinguishes among 10 elements must contain at least four bits, but 6 out of the 16 possible combinations remain unassigned. Different binary codes can be obtained by arranging four bits in 10 distinct combinations. The code most commonly used for the decimal digits is the straight binary assignment. This is called binary coded decimal. The gray code is used in applications where the normal sequence of binary numbers may produce an error or ambiguity during the transition from one number to the next. If binary numbers are used, a change from 0111 to 1100 may produce an intermediate erroneous number 1001 if the rightmost bit takes longer to change in value than the other three bits. The gray code eliminates this problem since only one bit changes in value during any transition between two numbers. (18)

19 Truth Table (Binary to Gray): Binary (Input) Gray (Output) B 3 B 2 B 1 B 0 G 3 G 2 G 1 G (19)

20 BCD to Excess 3 Vice versa: Excess 3 code is a modified form of a BCD number. The excess 3 code can be derived from the natural BCD code by adding 3 to each coded number. For example, decimal 6 can be represented in BCD as Now adding 3 to the given number yield equivalent excess 3 code i.e., = = Thus for the entire sequence of BCD value (i.e., 0 to 9) excess 3 equivalent table should be made so that the realization of Boolean expression for the circuit implementation is feasible. In the reverse process of designing a code converter from excess 3 to BCD the same procedure is followed. Here are the general steps to be followed while going for a code converter design, start with the specification of the circuit to be designed. Identify the inputs and outputs Derive truth table Obtain simplified Boolean equations Draw the logic diagram Check the design to verify correctness with the truth/verification table. (20)

21 Logic Diagram: Pin Diagram: (21)

22 Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. (22)

23 Truth Table (Gray to Binary): Gray (Input) Binary (Output) G 3 G 2 G 1 G 0 B 3 B 2 B 1 B (23)

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25 Logic Diagram: Truth Table: Decimal Value BCD Input Excess 3 output A B C D W X Y z (25)

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27 Realization of Boolean Expression for BCD to Excess 3 Converter: Circuit Diagram: (27)

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29 Truth Table: Decimal Value Excess 3 Input BCD Output W X Y z A B C D Realization of Boolean Expression for Excess 3 to BCD Converter: (29)

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31 Circuit Diagram: (31)

32 Description Max. Marks Marks Secured Preparation 30 Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the combinational circuit for an arbitrary function, code converter using logic gates was designed, implemented and tested its performance with truth table. (32)

33 Logic Diagram: Pin Diagram: (33)

34 EXP. NO : 3 DATE : DESIGN AND IMPLEMENTATION OF 4 BIT BINARY ADDER / SUBTRACTOR USING MSI DEVICES Aim: To design and implement a four bit binary adder / subtractor using MSI devices. Apparatus Required: S.NO COMPONENTS RANGE QUANTITY 1 IC trainer kit IC s Connecting wires - - Theory: Digital computers perform a variety of information processing tasks. Among the functions encountered are the various arithmetic operations. The most basic arithmetic operation is the addition of two binary digits. This simple addition consists of four possible elementary operations: 0+0=0, 0+1=1, 1+0=0 and 1+1=10. A binary adder-subtractor is a combinational circuit that performs the arithmetic operations of addition and subtraction with binary numbers. A combinational circuit that performs the addition of two bits is called half adder. One that performs the addition of three bits is a full adder. A binary adder is a digital circuit that produces the arithmetic sum of two binary numbers. Procedure: 1. Connect the circuit as per the circuit diagram. 2. Power supply is switched ON and a voltage of 5v is maintained. 3. Four bit binary number is given and verifies the sum result. 4. If the adder or subtractor signal is low addition is performed. 5. If the adder or subtractor signal is high subtractor result is verified. (34)

35 Verification Table: Terminology Input Variables Binary inputs Augend A 3 A 2 A 1 A 0 Addend B 3 B 2 B 1 B 0 Results C in C out Addition Subtraction (35)

36 Description Max. Marks Preparation 30 Marks Secured Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the 4 bit parallel adder/subtractor was implemented and tested using the MSI device IC (36)

37 Truth Table (Even and odd parity generator): Data Inputs Parity Bit D 1 D 2 D 3 D 4 Even Odd (37)

38 EXP. NO : 4 DATE : DESIGN AND IMPLEMENTATION OF PARITY GENERATOR AND CHECKER Aim: To design and implement the parity generator and checker using logic gates and verify its performance with the verification table. Components Required: S.NO COMPONENTS RANGE QUANTITY 1 Digital IC Trainer kit IC Connecting wires - As required 4 Bread board - 1 Theory: Parity generator: A parity bit is a scheme of detecting error during transmitting of binary information. A parity bit is an extra bit included with a binary message to make the number of 1 s either odd or even. Parity generators are used in digital transmission system for the errorless transmission of digital data. A parity bit is added to the data before the transmission and it will be checked for the correctness at the receiver end. There are two types of parity systems, even parity and odd parity. In the even parity system if the number of 1 s in the data word is odd, a 1 will be added as a parity bit to the data to make total number of 1 s even. If the number of 1 s even, a 0 bit will be added. In the odd parity system if the number of 1 s in the data word is odd, a 0 will be added to make the number of 1 s odd. Otherwise, a 1 is added to make it odd. The circuit shown in the figure is used as a parity generator as well as a checker. ABCD is the 4-bit data word. Pi and Po are the parity input and parity output respectively. The working of the circuit can be concluded as follows, Work as a Parity generator: To generate an odd parity bit for ABCD, Pi must be made 0. To generate an even parity bit for ABCD, Pi must be made1. Work as a parity checker: If the parity of ABCD Pi is odd, Po will be 0. If the parity of ABCD Pi is even, Po will be 1. (38)

39 Circuit Diagram: Pin Diagrams: (39)

40 The message, including the parity bit, is transmitted and then checked at the receiving end for errors. An error detected if the checked parity does not correspond with the one transmitted. The circuit that generates the parity bit in the transmitter is called a parity generator. The circuit that checks the parity in the receiver is called parity checker. In even parity the added parity bit will make the total number of 1s an even amount. In odd parity the added parity bit will make the total number of 1s an odd amount. Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. (40)

41 Truth Table for Even Parity Checker PARITY ERROR 4 BIT DATA RECEIVED CHECK A B C D PEC Circuit Diagram: K-Map Simplication for Even Parity Checker (41)

42 Description Max. Marks Marks Secured Preparation 30 Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the Parity Generator was designed, implemented using logic gates and its performance was verified. (42)

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44 EXP. NO : 5 DATE : DESIGN AND IMPLEMENTATION OF 2 BIT MAGNITUDE COMPARATOR AIM: To design and implement a 2-bit magnitude comparator using logic gates. COMPONENTS REQUIRED: S.NO COMPONENTS RANGE QUANTITY 1 Digital Trainer Kit IC s Connecting Wires / Patch Cords - As required 4. Bread board - 1 THEORY: The comparison of two numbers is an operation that determines if one number is greater than, less than, or equal to the other number. A magnitude comparator is a combinational circuit that compares the two numbers, A and B, and determines their relative magnitude. The circuit for comparing two n-bit numbers has 2 n entries in the truth table and becomes too cumbersome even with n=3. On the other hand comparator circuits possess a certain amount of regularity. The algorithm is a direct application of the procedure a person uses to compare the relative magnitudes of two numbers. Consider two numbers, A and B, with four digits each consider A=A 3 A 2 A 1 A 0 B=B 3 B 2 B 1 B 0 The two numbers are equal if all pairs of significant digits are equal: A 3 =B 3, A 2 =B 2, A 1 =B 1 and A 0 =B 0. When the numbers are binary, the digits are either 0 or 1, and the equality relation of each pair of bits can be expressed logically with an EX-OR function x i =A i B i + A i B i for i=0,1,2,3 The binary variables A=B=X 1 X 0 =1. A>B= A i B i + X 1 A 0 B 0 A<B = A i B i + X 1 A 0 B 0 (44)

45 Truth Table (2 Bit magnitude Comparator): Input Output A 1 A 0 B 1 B 0 A i = B i A i > B i A i < B i (45)

46 Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. Description Max. Marks Preparation 30 Marks Secured Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature RESULT: Thus the 2 bit magnitude comparator was constructed using logic gates and verified with its truth table. (46)

47 Implementation of the following Boolean function F=Σ m (1, 3, 5 6) using multiplexer Truth table Minterm Inputs A B C Output (F) Logic diagram: (47)

48 EXP. NO : 6 DATE : DESIGN AND IMPLEMENTATION OF APPLICATION USING MULTIPLEXERS Aim: To design and implement the combinational logic using multiplexers Components required: S. No Components Name Range Type Quantity 1 Digital IC trainer kit IC IC IC Bread Board Connecting wires - - As required Theory: The Block diagram shows the implementation of Boolean function using 4:1 multiplexer. The implementation table is nothing but the list of the inputs of the multiplexer and under them list of all the minterms in two columns. The first column lists all the minterms where least significant variable is complemented (C ), and the second column lists all the minterms with least significant variable is un-complemented (C). The minterms given in the function are circled and then each row is inspected separately as follows. If the two minterms in a row are not circled, 0 is applied to corresponding multiplexer input. If the two minterms in a row are circled, 1 is applied to corresponding multiplexer input. If the minterm in the column 1 is circled, least significant variable is complemented (C ) and applied to the corresponding multiplexer input. If the minterm in the column 2 is circled, least significant variable is uncomplemented (C) and applied to the corresponding multiplexer input. (48)

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50 Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. Description Max. Marks Preparation 30 Marks Secured Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the implementation of the given Boolean function using multiplexer was designed, implemented and verified with its truth table. (50)

51 Circuit Diagram: Serial IN Serial OUT shift Register Circuit Diagram: Serial IN Parallel OUT shift Register (51)

52 EXP. NO : 7 DATE : DESIGN AND IMPLEMENTATION OF SHIFT REGISTERS Aim: To design, implement and verify the functioning of shift right registers (all types) using D flip-flop. Components Required: S.NO COMPONENTS RANGE QUANTITY 1 Digital IC trainer kit ICs Connecting wires Bread Board - 1 Theory: A register that is used to store binary information is known as a memory register. A register capable of shifting binary information either to the right or the left is called a shift register. Shift registers are classified into four types, 1. Serial-in Serial-out (SISO) 2. Serial-in Parallel-out (SIPO) 3. Parallel-in Serial-out (PISO) 4. Parallel-in Parallel-out (PIPO) Serial-in Serial-out (SISO): This type of shift registers accepts data serially, i.e., one bit at a time on a single input line. It produces the stored information on its single output and the output also in serial form. Data may be shifted left (from low to high order bits) using shift-left register or shifted right (from high to low order bits) using shift-right register. Serial-in Parallel-out (SIPO): It consists of one serial input, and outputs are taken from all the flip-flop simultaneously in parallel. In this register, data is shifted in serially but shifted out in parallel. In order to shift the data out in parallel, it is necessary to have all the data available at the outputs at the same time. Once the data is stored, each bit appears on its respective output line and all the bits are available simultaneously, rather than on a bit by bit basis as with the serial output. Parallel-in Serial-out (PISO): This type of shift register accepts data parallel, i.e., the bits are entered simultaneously into their respective flip-flops rather than a bit-by-bit basis on one line. (52)

53 Circuit Diagram: Parallel-in Serial-out shift Register Circuit Diagram: Parallel IN Parallel OUT shift Register (53)

54 Parallel-in Parallel-out (PIPO): In this type of register, data inputs can be shifted either in or out of the register in parallel. Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. (54)

55 Verification Table: Pin Diagram: (55)

56 Description Max. Marks Preparation 30 Marks Secured Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the shift registers using D flip-flop were implemented and studied their operation in 4 different modes. (56)

57 State Table (3 bit synchronous binary UP counter) Present State Next State JK Flip-Flop Inputs A B C A + B + C + J A K A J B K B J C K C X 0 X 1 X X 1 X X X X 0 1 X X X 1 X X 0 0 X 1 X X 0 1 X X X 0 X 0 1 X X 1 X 1 X 1 JK Excitation Table: Q n Q n+1 J K X X 1 0 X X 0 (57)

58 EXP. NO : 8 DATE : DESIGN AND IMPLEMENTATION OF SYNCHRONOUS COUNTER Aim: To design and implement a 3-bit synchronous binary up and down counter using JK flip-flop. Components Required: S.NO COMPONENTS RANGE QUANTITY 1 Digital Trainer Kit IC s Connecting wires - As required 4 Bread Board - 1 Theory: A Synchronous counter is also called parallel counter. In this counter the clock inputs of all the flip-flops are connected together so that the input clock signal is applied simultaneously to each flip-flop. Also, only the LSB flip-flop C has its J and K inputs connected permanently to Vcc while the J and K inputs of the other flip-flops are driven by some combination of flip-flop outputs. 3 Bit Synchronous Binary UP Counter: The J and K inputs of the flip-flop B are connected to with Q C. The J and K inputs of the flip-flop A, are connected with AND operated output of Q C and Q B. The flip-flop C changes its state when with the occurrence of negative transition at each clock pulse. The flip-flop B changes its state when Q C = 1 and when there is negative transition at clock input. Flip-flop A changes its state when Q C = Q B = 1 and when there is negative transition at clock input. 3 Bit Synchronous Binary DOWN Counter: The J and K inputs of the flip-flop B are connected to with Q C. The J and K inputs of the flip-flop A, are connected with AND operated output of Q C and Q B. The flip-flop C changes its state when with the occurrence of negative transition at each clock pulse. The flip-flop B changes its state when Q C = 1 and when there is negative transition at clock input. Flip-flop A changes its state when Q C = Q B = 1 and when there is negative transition at clock input. (58)

59 Circuit Diagram: (59)

60 Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. Pin Diagram: (60)

61 State Table (3 bit synchronous binary DOWN counter) Present State Next State JK Flip-Flop Inputs A B C A + B + C + J A K A J B K B J C K C X 1 X 1 X X 0 X X X X 1 1 X X X 0 X X 1 1 X 1 X X 0 0 X X X 0 X 1 1 X X 0 X 0 X 1 JK Excitation Table: Q n Q n+1 J K X X 1 0 X X 0 Circuit Diagram: (61)

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63 State Table: Present State Next State T input D C B A D + C + B + A + T D T C T B T A Realization of T flip-flop input using K- Map: (63)

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65 T flip-flop Excitation Table: Q n Q n+1 T Circuit Diagram: (65)

66 Description Max. Marks Preparation 30 Marks Secured Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the synchronous up, down and BCD counters were designed using JK flip-flop and verified with their state table. (66)

67 Verification Table (4 bit binary ripple up counter): Clock Pulse Q 3 Q 2 Q 1 Q Circuit Diagram: (67)

68 EXP. NO : 9 DATE : DESIGN AND IMPLEMENTATION OF ASYNCHRONOUS COUNTER Aim: To design and implement a 4-bit asynchronous binary up and down counter using JK flip-flop. Components Required: S.NO COMPONENTS RANGE QUANTITY 1 Digital IC trainer kit IC Bread board Connecting wires - As required Theory: A counter, by function, is a sequential circuit consisting of a set of flip-flops connected in a suitable manner to count the sequence of the input pulses presented to it digital form. An asynchronous counter, each flip-flop is triggered by the output from the previous flip-flop which limits its speed of operation. The settling time in asynchronous counters, is the cumulative sum of the individual settling times of flip-flops. It is also called a serial counter. The asynchronous counter is the simplest in terms of logical operations, and is therefore the easiest to design. In this counter, all the flip-flops are not under the control of a single clock. Here, the clock pulse is applied to the first flip-flop, i.e. the least significant bit stage of the counter, and the successive flip-flop is triggered by the output is constructed using clocked JK flip-flops. The system clock, a square wave, drives flipflop A (LSB). The output of A drives flip-flop B, the output of B drives flip-flop C. all the J and K inputs connected to Vcc (High (1)), which means that each flip-flop toggles on the edge (-ve) clock pulse. Consider initially all flip-flops to be in the logical 0 state (i.e. Q A =Q B =Q C =Q D =0). A negative transition in the clock input which drives flip-flop A causes Q A to change from 0 to 1. Flip-flop B doesn t change its state since it is also requires negative transition at its clock input, i.e. it requires its clock input (Q A ) to change from 1 to 0. With arrival of second clock pulse to flip-flop A, Q A goes from 1 to 0. This change of state creates the negative going edge needed to trigger flip-flop B, and thus Q B goes from 0 to 1. Before the arrival of the 16 th clock pulse, all the flip-flops are in the logical 1 state. Clock pulse 16 causes Q A, Q B, Q C and Q D to go logical 0 state in turn. (68)

69 Verification Table (4 bit binary ripple down counter): Clock Pulse Q 3 Q 2 Q 1 Q Circuit Diagram: (69)

70 Procedure: 1. Test the individual ICs with its specified verification table for proper working. 2. Connections are made as per the circuit/logic diagram. 3. Make sure that the ICs are enabled by giving the suitable V cc and ground connections. 4. Apply the logic inputs to the appropriate terminals of the ICs. 5. Observe the logic output for the inputs applied. 6. Verify the observed logic output with the verification/truth table given. Pin Diagram: (70)

71 Verification Table (BCD ripple up counter): Clock Pulse Q 3 Q 2 Q 1 Q Circuit Diagram: (71)

72 Description Max. Marks Preparation 30 Marks Secured Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the asynchronous up, down and BCD counters were constructed and tested the operations with the help of their verification tables. (72)

73 HDL for combinational logic library ieee; use ieee.std_logic_1164.all; entity gor is port(a,b: in std_logic; c:out std_logic); end gor; architecture arc_gor of gor is begin c <= a or b; end arc_gor; VHDL code for logic gates OR gate library ieee; use ieee.std_logic_1164.all; entity nandg is port(a,b: in std_logic; c:out std_logic); end nandg; architecture arc_ nandg of nandg is begin c <= a nand b; end arc_ nandg; VHDL code for logic gates NAND gate library ieee; use ieee.std_logic_1164.all; entity gxor is port(a,b: in std_logic; c:out std_logic); end gxor; architecture arc_gxor of gxor is begin c <= a xor b; end arc_gxor; VHDL code for logic gates Ex-OR gate (73)

74 EXP. NO : 10 DATE : Aim: HDL FOR COMBINATIONAL LOGIC To write a VHDL code for the combinational circuits given below and simulate the result using EDA tool. 1. Logic Gates (OR, NAND and EX-OR) 2. Half adder and Full adder Components Required S.No Component Name Range / Type Quantity 1 Personal Computer EDA Tool (ModelSim 5.5e) - - Theory: The basic steps involved in the Digital System Design are, 1. Specify the desired behavior of the circuit. 2. Synthesize the circuit. 3. Implement the circuit. 4. Test the circuit to check whether the desired specifications meet. But as the size and complexity of digital system increase, they cannot be designed manually because their design becomes highly complex. At their most detailed level, they may consist of millions of elements (Transistors or logic gates). So, Computer aided design (CAD) tools are used in design of digital systems. One such a tool is a Hardware Description Language (HDL). HDL describes the hardware of digital systems. This description is in textual form. The Boolean expressions, logic diagrams and digital circuits (Simple and Complex) can be represented using HDL. The HDL provides the digital designer with a means of describing a digital system at a wide range of levels of abstraction and at the same time, provides access to computer aided design tools to aid in the design process at these levels. The HDL represents digital systems in the form of documentation which can understand by human as well as computers. It allows hardware designers to express their design with behavioral constructs. An abstract representation helps the designer explore architectural alternatives through simulations and to detect design bottlenecks before detailed design begins. The HDL makes it easy to exchange the ideas between the designers. It resembles a programming language, but the orientation of the HDL is specifically towards describing hardware structures and behavior. The storage, retrieval and processing of programs written using HDL can be performed easily and efficiently. HDL s are used to describe hardware for the purpose of simulation, modelling, testing and documentation. (74)

75 -- Library Declaration library ieee; use ieee.std_logic_1164.all; use work.all; -- Entity Declaration entity fa is port (a,b,c:in std_logic; sum,cout: out std_logic); end fa; VHDL for full adder Structural Model -- Architecture Declaration Structural Model architecture arc_fa of fa is component ha port(a,b:in std_logic; s,c:out std_logic); end component; component gor port(a,b:in std_logic; c:out std_logic); end component; signal s1,c1,c2:std_logic; begin ha1:ha port map(a,b,s1,c1); ha2:ha port map(s1,c,sum,c2); or1:gor port map(c1,c2,cout); end arc_fa; library ieee; use ieee.std_logic_1164.all; entity ha is port ( a,b: in std_logic; s,c: out std_logic); end ha; architecture arc_ha of ha is begin s <= a xor b; c <= a and b; end arc_ha; VHDL for half adder Data Flow Model (75)

76 Procedure: 1. Click the ModelSim SE 5.5e icon to start the simulation of VHDL code. 2. Select create a project options given on the welcome screen in order to create a new project otherwise choose open a project to open the existing project. 3. Proper project name should be given along with the location to save the project in the create project window. 4. In the main window go to file New Source VHDL to get in to the source editor window. 5. Enter the VHDL source code on that source editor window and save with the extension.vhd in the project (project created) folder and location specified previously. 6. Select file compile in the source editor window for compiling the written code. If there is an error debug the error, save and compile again. 7. Load the design by selecting Design load design in the main window after successful compilation of the VHDL codes. 8. Select signals from the view menu of the main window for selecting the signals. 9. In signal window, choose edit force / clock for applying the appropriate input levels for the signals selected. 10. Select view wave signals in design to view the response of the design (Wave form) with the help of run option from the signal window. 11. Continue the simulation for different input levels with the procedure stated above. Description Max. Marks Marks Secured Preparation 30 Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the VHDL Code for the Combinational circuits was developed and simulated using Electronic Design Automation tool. (76)

77 HDL FOR SEQUENTIAL LOGIC library ieee; use ieee.std_logic_1164.all; entity dff is port(clr,d : in std_logic; clk: in std_logic; q : out std_logic); end dff; architecture arc_dff of dff is begin process(clk) begin if(clr = '0')then q <= '0'; elsif (clk = '1' and clk'event) then q <= d; end if; end process; end arc_dff; VHDL code for flip-flops (D) VHDL for Synchronous UP/DOWN counter Library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity synudcounter is port( clk: in std_logic; clr: in std_logic; ud: in std_logic; cout: inout std_logic_vector(3 downto 0)); end synudcounter; architecture arc_synudcounter of synudcounter is begin process(clk) begin if (clk = '0' and clk'event) then if(clr = '0') then cout <= "0000"; else if(clr = '1' and ud = '0') then cout <= cout + 1; elsif(clr = '1' and ud = '1') then cout <= cout - 1; end if; end if; end if; end process; end arc_synudcounter; (77)

78 EXP. NO : 11 DATE : Aim: HDL FOR SEQUENTIAL LOGIC To write a VHDL code for the sequential circuits given below and simulate the result using EDA tool. 1. D flip flop 2. Synchronous UP / DOWN Counter Components Required S.No Component Name Range / Type Quantity 1 Personal Computer EDA Tool (ModelSim 5.5e) - - Theory: The basic steps involved in the Digital System Design are, 1. Specify the desired behavior of the circuit. 2. Synthesize the circuit. 3. Implement the circuit. 4. Test the circuit to check whether the desired specifications meet. But as the size and complexity of digital system increase, they cannot be designed manually because their design becomes highly complex. At their most detailed level, they may consist of millions of elements (Transistors or logic gates). So, Computer aided design (CAD) tools are used in design of digital systems. One such a tool is a Hardware Description Language (HDL). HDL describes the hardware of digital systems. This description is in textual form. The Boolean expressions, logic diagrams and digital circuits (Simple and Complex) can be represented using HDL. The HDL provides the digital designer with a means of describing a digital system at a wide range of levels of abstraction and at the same time, provides access to computer aided design tools to aid in the design process at these levels. The HDL represents digital systems in the form of documentation which can understand by human as well as computers. It allows hardware designers to express their design with behavioral constructs. An abstract representation helps the designer explore architectural alternatives through simulations and to detect design bottlenecks before detailed design begins. The HDL makes it easy to exchange the ideas between the designers. It resembles a programming language, but the orientation of the HDL is specifically towards describing hardware structures and behavior. The storage, retrieval and processing of programs written using HDL can be performed easily and efficiently. HDL s are used to describe hardware for the purpose of simulation, modelling, testing and documentation. (78)

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80 Procedure: 1. Click the ModelSim SE 5.5e icon to start the simulation of VHDL code. 2. Select create a project options given on the welcome screen in order to create a new project otherwise choose open a project to open the existing project. 3. Proper project name should be given along with the location to save the project in the create project window. 4. In the main window go to file New Source VHDL to get in to the source editor window. 5. Enter the VHDL source code on that source editor window and save with the extension.vhd in the project (project created) folder and location specified previously. 6. Select file compile in the source editor window for compiling the written code. If there is an error debug the error, save and compile again. 7. Load the design by selecting Design load design in the main window after successful compilation of the VHDL codes. 8. Select signals from the view menu of the main window for selecting the signals. 9. In signal window, choose edit force / clock for applying the appropriate input levels for the signals selected. 10. Select view wave signals in design to view the response of the design (Wave form) with the help of run option from the signal window. 11. Continue the simulation for different input levels with the procedure stated above. Description Max. Marks Marks Secured Preparation 30 Performance 40 Viva Voce 10 Record 20 Total 100 Staff Signature Result: Thus the VHDL Code for the Sequential circuits was developed and simulated using Electronic Design Automation tool. (80)

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