Basic UART TX/RX module for FPGA

A simple UART TX/RX module implemented using Verilog HDL for FPGA

How it works

The UART TX/RX module is internally projected to work with any baud rate of user choice.
That has to be done through module instantiation parameters:

TICKS_PER_BIT       : Number of clock ticks for a bit time (ticks per bit = system clock / baud rate)
TICKS_PER_BIT_SIZE  : Number of bits to hold TICKS_PER_BIT value, usually obtained using $bits(TICKS_PER_BIT);

Note that the baud rate can’t be ajusted on-the-fly, it just can be done in compilation / synthesis time.

Those modules is simple designed, no complexity such as parity bit or two stop bits is implemented.

UART TX module

Module inputs:

i_clk        : System clock
i_start      : Start pulse
[7:0] i_data : Data to be send

Module outputs:

o_done       : Done pulse output
o_busy       : Busy signal output
o_dout       : Data out (TX) output

Module Waveform:

UART RX module

Module inputs:

i_clk       : System clock
i_enable    : RX enable signal
i_din       : Data in (RX)

Module outputs:

[7:0] o_rxdata  : Data received
o_recvdata      : Data received pulse
o_busy          : Busy signal output

Module Waveform:

Prerequisites

Any Verilog compiler tool and a logic waveform analyzer, for instance: GTK Wave.

A FPGA (optional).

Compile and test

1. Compile the source code using Icarus Verilog:

iverilog -o uart_tb.out uart_tb.v

1. Executing the compiled file (run the tests):

vvp uart_tb.out

1. Opeing the waveform analyzer:

gtkwave uart_tb.vcd

Explaining the testbench

The testbench script perform a series of stimulus on UART RX/TX modules, and those can be analyzed to check if the module behaviour is working as expected.

The module was tested successfully on Altera Cyclone II and works fine using a such low resources from FPGA.

Versioning

17/10/2018 - Initial work (V1.0)

Authors

• Matheus Alencar Nascimento - Initial work

License

This project is licensed under the MIT License - see the [LICENSE] file for details

Acknowledgments

• Nandland Website