Finite State Machine Serial Adder
Abstract— Logic design is in itself bifurcated to- Combinational and Sequential circuits. The later has memory and former doesn’t, so in an advent effort to incorporate memory into a combinational circuit brought in the concept of Finite state machine serial adder.
Finite state machines — FPGA designs with VHDL documentation. Finite state machines ¶. In previous chapters, we saw various examples of the combinational circuits and sequential circuits. In combinational circuits, the output depends on the current values of inputs only; whereas in sequential circuits, the output. State diagram for serial adder: Let S0 and S1 are the states where the carry in values is '0' and '1' respectively. Figure shows the suitable state diagram defined as a mealy model. The output value sum depends on both state and the present value of the inputs a and b, each transition is labeled using the notation ab / sum which indicates the.
Keywords— D-latch, Finite state machine, Mealy Model, Multisim, Serial adder
I. INTRODUCTION TO FINITE STATE MACHINE
A finite state machine can be represented by a state transition table or a state diagram. There is often a fixedstart state which is the initial state of the Finite State Machine (before any input has been read). Thus a finite state machine (FSM) is a model describing the behavior of a finite number of states, the transitions between those states, and actions [1].
Car Parking System in VHDL. This VHDL project presents a car parking system in VHDL using Finite State Machine (FSM). VHDL code and testbench for the car parking system are fully provided. The VHDL car parking system is shown in the following figure. There is a front sensor to detect vehicles going to the gate of the car parking system. Aug 25, 2018 A finite-state machine (FSM) is a mechanism whose output is dependent not only on the current state of the input, but also on past input and output values. Whenever you need to create some sort of time-dependent algorithm in VHDL, or if you are faced with the problem of implementing a computer program in an FPGA, it can usually be solved. Dec 13, 2011 Finite State Machine (FSM) Coding In VHDL. There is a special Coding style for State Machines in VHDL as well as in Verilog. Let us consider below given state machine which is a “1011” overlapping sequence detector. Output becomes ‘1’ when sequence is detected in state S4 else it remains ‘0’ for other states.
Parallel Adder
II. SERIAL ADDER
The serial binary adder or bit-serial adder is a digital circuit that performs binary addition bit by bit. The serial full
adder has three single-bit inputs, two for addition and one for carry in(C-in). There are two single-bit outputs for the sum and carry out(C-out). The C-in signal is the previously calculated C-out signal. Adding each bit, lowest to highest, one per clock cycle, performs the addition [2]. Fig 1 shows a basic structure of a FSM serial adder.
Serial Adder Circuit
Fig 1: Block diagram of a serial adder[2]
The design is based on Mealy model. Let us consider two states, G & H i.e. when carry is generated we take H state &
when carry is zero we take G state. A & B are taken as the inputs to the serial adder. Table 1 shows the state table of the serial adder [2].
Table 1: STATE TABLE of SERIAL ADDER[2]
Vhdl Code For Serial Adder Using Finite State Machines
Based on the state table we can construct the state diagram. The state diagram is as shown in Fig 2. As observed in the state figure as long as the there is no carry generated, it stays in state G. but if there is a carry generated, it immediately moves to state H. In this state carry is added to the sum. When sum of A & B does not create a carry it moves back to state G.