Hi Daiane,
I've found that a command "hciattach" was required to make the kernel recognize the device.
This command was successful on the PC Linux and Ubuntu i.mx53. But I didn't make it on Android platform.
This might be because the specified device was incorrect. I guess that is "ttymxcX".
Do you know what device the serial port is regarded as?
Best Regards,
Takashi Kawamoto