    </tr>
    <tr>
        <td>data_valid</td>
        <td>input</td>
        <td align="center">1</td>
        <td>A signal that indicates that there exist data to be transmitted.</td>
    </tr>
    <tr>
        <td>parallel_data</td>
        <td>input</td>
        <td align="center">DATA_WIDTH (default value is 8)</td>
        <td>The data to be transmitted by the UART transmitter.</td>
    </tr>
    <tr>
        <td>serial_data_out</td>
        <td>output</td>
        <td align="center">1</td>
        <t