Quote Originally Posted by HenrikOlsson View Post
Since you don't say which Bluetooth module you're using I can't tell what size the buffer is but if you keep feeding that buffer faster than the module is able to send the data out over the air it will eventually overflow and things happens as a result. As a test try a 1 second delay, if it seems to work you've probably found the cause and can start to think about what to do about it.

If the Bluetooth module have flow control pins it might be a good option.

I'm not saying this IS the issue but it's something I'd try.

I'm using an HC-05 module to send data to a PC or cellphone.