uart_tx

UART Transmitter

UART transmitter developed to be as easy to use as possible. It supports 8-bit data transmission with one stop bit and no parity bit - the most common configuration.

To start the transmission, feed the data to be sent to the Data_i input and set the Start_i input high for the length of one clock cycle. You can then set the next byte to be sent, but wait until the Done_o output is high. Then you can transmit the next byte. To speed up communication, you can loop the Done_o output with the Start_i input so that the completion of sending a byte starts sending the next one.

Instantiation

	UartTx #(
		.CLOCK_HZ(CLOCK_HZ),
		.BAUD(115200)
	) DUT(
		.Clock(Clock),
		.Reset(Reset),
		.Start_i(),
		.Data_i(),
		.Busy_o(),
		.Done_o(),
		.Tx_o()
	);

Port description

• CLOCK_HZ - Clock signal frequency [Hz].
• BAUD - Bits per second.
• Clock - Clock signal, active rising edge.
• Reset - Asynchronous reset, active low.
• Start_i - High strobe initiates the transmission.
• Data_i[7:0] - A byte to be transmitted.
• Busy_o - High as long as transmission is in progress.
• Done_o - A single high pulse signals the end of the operation. New data can be loaded at this moment using Start_i and Data_i.
• Tx_o - The output of UART transmitter.

Simulation

Example of transmitting Hello at 100000 baud.

Console output

VCD info: dumpfile uart_tx.vcd opened for output.
===== START =====
Ticks per bit =        10
====== END ======
uart_tx_tb.v:91: $finish called at 700000 (1ns)