Bluetooth RFCOMM with Microsoft stack

Question

I have set up a connection between a Bluetooth module and a PC (Bluetooth USB dongle) on the RFCOMM protocol. On the PC side, I am interfacing with the Microsoft windows stack through an API though there is no Method in the API to specify the Baudrate.

What is the connection datarate? Isn't it supposed to emulate RS-232 baudrates?

I Have used a terminal program to write/read from the appearing virtual COM port (without the api) and it seems that the driver wouldn't allow setting more than 115200 baudrate for the virtual COM port. Is this taking any effect when choosing a specific baudrate?

Answer 1

SPP is a cable replacement profile e.g. one of the RS-232 D9 cables used to connect serial ports. Setting the baud rate, etc... is so that this can be communicated to the device at the other end of the virtual cable, to set it's baud rate. Like-wise with the CTS, RTS - they just get communicates to the other end.

SPP does not and cannot emulate baud rate over the air. The data rate is going to be whatever the particular manufacturer's Bluetooth chip can provide. This is usually well short of spectacular.

You might as well use an RFCOMM link and save a little latency.

Answer 2

I have never know of any reason to set baud-rate, line settings, or line signals (CTS, RTS) etc on a Bluetooth RFCOMM connection. You'll likely find the same...

In the case where a Serial to Bluetooth converter is being used, normally the converter is configured directly once to suit the bit-rate of the legacy equipment to which it is attached and never again.