$this->load->helper('download');

$blanks = array("t","t","t","t");

$fp = fopen('php://output', 'w');
foreach ($writedata as $fields) { //table one
fputcsv($fp, $fields);
}

for($i=0;$i<5;$i++)
{
foreach ($blanks as $fields) { //blank space insertion try
fputcsv($fp, $fields);
}
}

foreach ($table2 as $fields) { //table two
fputcsv($fp, $fields);
}
$data = file_get_contents('php://output');
$name = 'data.csv';

<?php

$this->load->helper('download');

$fp = fopen('php://output', 'w');
foreach ($writedata as $fields) { //table one
    fputcsv($fp, $fields);
}

for($i=0;$i<5;$i++) {
    fput($fp, PHP_EOL);
}

foreach ($table2 as $fields) { //table two
    fputcsv($fp, $fields);
}
$data = file_get_contents('php://output');
$name = 'data.csv';

$this->load->helper('download');

$blanks = array("t","t","t","t");

$fp = fopen('php://output', 'w');
foreach ($writedata as $fields) { //table one
    fputcsv($fp, $fields);
}

for($i=0;$i<5;$i++) {
    fputcsv($fp, $blanks);
}

foreach ($table2 as $fields) { //table two
    fputcsv($fp, $fields);
}
$data = file_get_contents('php://output');
$name = 'data.csv';

$this->load->helper('download');

            $blanks = array();
            for($i=0;$i<5;$i++)
            {

            array_push($blanks,array("t","t","t","t");
            }

            $fp = fopen('php://output', 'w');
            foreach ($writedata as $fields) {
                fputcsv($fp, $fields);
                }

            foreach ($blanks as $fields) {
                    fputcsv($fp, $fields);
                    }

            foreach ($table2 as $fields) {
                fputcsv($fp, $fields);
                    }
            $data = file_get_contents('php://output');
            $name = 'data.csv';