05 January 2009

USB Bluetooth to Serial

I wrote about a crap Bluetooth dongle that I bought last year. I was terked about the big honkin' plastic case with a fake antenna. While looking at the pcb, I noticed that it was a Cambridge Silicon Radio (CSR) chip labeled BC212 015BD A21AA. At the time, I did a quick Google search on the part number and moved on after not seeing anything too interesting.

Tonight I read a post on the Arduino Forum about cheap Bluetooth that said most USB Bluetooth dongles were "just a USB Serial Com device for the Bluetooth software stack to talk to". What?!? No frickin' way. A USB dongle is a USB Slave device that requires a USB Master device to interfaces with it. Isn't that so?

Mr Dougl's (junior member) post started me thinking about that Bluetooth crap thing. There's no way that it's just a serial port device. I went back to that quick Google search and began reviewing the hits. This one seems interesting. A Bluetooth RS232 to Bluetooth Adapter. And it uses the same CSR BT chip as my crap. Hmmm. Could my chip have a simple serial interface? And if it does, can I interface this crap to the simple serial rx/tx interface of an Arduino?

A little more digging uncovered the CSR BlueCore DataBook that says the BC212 has both a USB and UART interface.

First thing I noticed here is the module uses CTS/RTS handshaking, which is currently a bit of a rough spot with Arduino. Another deal breaker may be the words above that say "requires external RS232 transceiver IC". I dunno. I'll look at this again soon and see if any progress can be made.