CodeIgniter 2.x generate pdf then redirect page

Question

I have problem with redirect page in codeigniter. to the point :

I have 2 functions in one controllers like below :

1. function to generate pdf (download)

   function generate_sprint()        
   {
   $tanggal = mdate('%d');
   $tahun = mdate('%Y');
   $bulan = mdate('%m');
   $tanggal_masuk = $this->input->post('tanggal_masuk');
   $bulan_masuk = $this->input->post('bulan_masuk');
   $tahun_masuk = $this->input->post('tahun_masuk');
   
   $no_spt = '1';
   $bln_spt = $bulan;
   $thn_spt = $tahun;
   $data['no_spt'] = 'No : ' . $no_spt . ' / CSI - HRD / SPT / ' .$bln_spt. ' / ' . $thn_spt;
   $data['waktu'] = "".$tanggal." ".$bln." ".$tahun;
   $data['creator'] = $this->session->userdata('nama');
   $data['nik'] = $this->app_model->GenerateNIK();
   $data['jabatan'] = $this->input->post('jabatan');
   $data['nama'] = $this->input->post('nama');
   $data['tgl_masuk'] = $tanggal_masuk." ".$bln." ".$tahun_masuk;
   $data['site_name'] = $this->app_model->CekSiteName();
   
   $info =  "".$data['nik']." , ".$data['nama']." , ".$data['jabatan'];
   $this->load->library('ciqrcode');   
   $params['data'] = $info;
   $params['level'] = 'H';
   $params['size'] = 5;
   $params['savename'] = FCPATH.'MyCode.png';
   $bar = $this->ciqrcode->generate($params);
   
   $data['barcode'] = $bar;
   $this->load->view('karyawan/generate_sprint', $data);
   }
   

2. function for processing data (input)

   $this->app_model->insertData("biodata_karyawan",$in);
   $this->app_model->insertData("absensi_karyawan",$in2);
   $this->generate_sprint(); --> this is for execute generate pdf

redirect(base_url() . 'karyawan_front/tambah/' . $site, 'refresh' ); --> after that the page will be direct

Can someone help me?

thanks for your time guys...

Regards