Upload string value to file - PHP

I need to upload a simple string via api - there is no "file" on the server - the string will be generated in my PHP code. First, does it need to be in binary? Second, when I upload, I get a "1" written into a file - and thats it. How do I get that string uploaded? I don't get any errors back. Help!

 

 

$fields = array(
   "path" => "/ba.txt",
   "autorename" => false,
   "mode" => "overwrite",
   "mute" => false,
   "strict_conflict" => false );

$string = 'hello there';
$binary = strigToBinary($string).PHP_EOL;

$headers = array(
   'Authorization: Bearer ' . $auth_token,
   'Content-Type: application/octet-stream',
   'Dropbox-API-Arg: '.json_encode($fields)
 );

$ch = curl_init();
curl_setopt($ch, CURLOPT_POSTFIELDS, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_URL, 'https://content.dropboxapi.com/2/files/upload');
curl_setopt($ch, CURLOPT_INFILE, $binary);

 

 

and here is my binary function

 

function strigToBinary($string) {
    $characters = str_split($string);
    $binary = [];
    foreach ($characters as $character) {
        $data = unpack('H*', $character);
        $binary[] = base_convert($data[1], 16, 2);
    }
    return implode(' ', $binary);    
}