I started a new topic: "OS X issues" with focus only on the OS X specific problems/changes, etc.
The Logic Analyzer helped me to understand the lower communication speed over Bluetooth.
The timing of the Bluetooth stack in the OS X seems to be ugly.
Instead of expected ~50ms pauses between data chunks I observed ~250ms pauses (200ms additional delay in OSX BT stack?)
Additionally bigger data chunks were not transmitted in one shot.
With "bigger" I mean a diskette sector + checksum (129 bytes), There was a 200ms pause in between.
The virtual serial port is opened with O_NDELAY parameter, so the "read()" and "write()" calls are non blocking.
The "write()" call will not necessarily process all bytes. It returns the number of bytes that could be written.
The still awaiting bytes have to be sent in the next "write()" call (in a loop) and this happens for 129 bytes (sent in to chunks: 126 + 3)
At the end, the data transfer was successful, but I don't have any idea how to improve that
Edited by TheMontezuma, Wed Feb 3, 2016 3:26 AM.