A) Write the Verilog code and testbench for a 16-bit Serial adder using Moore FSM design technique. B) Why are 4 and 5-input LUTs are preferred in FPGAs and why not higher input LUTs like 10 or 12 or much higher not used? C) What is a tristate buffer and how is it synthesized using Verilog HDL? Serial input of addends (inA, inB), LSB first; Serial generation of sum bits, LSB first (sum) Enable signal (en) to start computation; Done signal (done) on last computation (MSB. This Verilog project is to present a full Verilog code for Sequence Detector using Moore FSM. A Verilog Testbench for the Moore FSM sequ. Basys 3 FPGA OV7670 Camera.
The serial adder is a digital circuit in which bits are added a pair at a time.
Let A and B be two unsigned numbers to be added to produce Sum = A + B. In this we are using three shift registers which are used to hold A, B and Sum. Now in each clock cycle, a pair of bits is added by the adder FSM and at the end of the cycle, the resulting sum is shifted into the Sum register.
Mealy type FSM for serial adder:
Let G and H denote the states where the carry-in-values are 0 and 1. Output value s depends on both the state and the present value of inputs a and b.
In state G and H:
| Input valuation | Output (s) | State |
|---|---|---|
| 00 | 0 | FSM will remain in same state G |
| 01,10 | 1 | FSM will remain in same state G |
| 11 | 0 | FSM moves to state H |
| 01,10 | 0 | FSM will remain in same state H |
| 11 | 1 | FSM will remain in same state H |
| 00 | 1 | FSM moves to state G |
A single Flip-Flop is needed to represent the two states. The next state and output equations are:
Y = ab + ay + by
s = a ⊕ b ⊕ y
The flip-flop can be cleared by the Reset signal at the start of the addition operation.
Moore type FSM for serial adder:
In a Moore type FSM, output depends only on the present state. Since in both states, G and H, it is possible to produce two different outputs depending on the valuations of the inputs a and b, a Moore type FSM will need more than two states. Therefore we will four states namely: G0, G1, H0 and H1.
The next state and output equations are:
Y1 = a ⊕ b ⊕ y2
Four Bit Adder Verilog
Y2 = ab + by2 + by2
Bcd Adder Verilog
s = y1
Full Adder Verilog Code
The only difference between circuits of Mealy and Moore type FSM for serial adder is that in Moore type FSM circuit, output signal s is passed through an extra flip-flop and thus delayed by one clock cycle with respect to the Mealy type FSM circuit.
4 Bit Ripple Adder Verilog
References: Fundamentals of Digital Logic with VHDL Design
Comments are closed.