User's Manual

Fender FMA BT-FTSW-USB PCBA (PN 7710068000) Page 1
Manual and Spec, revision 1.0 November 8, 2016
Fender FMA BT-FTSW-USB PCBA (PN 7710068000)
Manual and Spec, revision 1.0
Module Description
The Fender FMA BT-FTSW-USB PCB Assembly is an auxiliary PCB used in the family of Fender Modular
Architecture (FMA) products. The board has a USB port with a micro AB connector, a Fender Footswitch
port with a ¼” phone jack and a wireless module.
Circuit Description/Theory of Operation
There are three main sections of the circuit:
• Bluetooth module (FreeWings FW3817-30), antenna, & audio output circuit
• USB port
• Footswitch port
The USB circuit consists of ESD protection components and a micro AB USB connector. The Footswitch
circuit consists of ESD protection components and a ¼” phone jack connector. Both of these circuits are
unrelated to the Bluetooth section, and are shared on the PCB for mechanical convenience.
The FreeWings module is a complete Bluetooth implementation with analog audio output. An F-style
antenna is connected to the RF output of the module through a test switch and matching network. The
module is powered with a 3.3V DC supply and digital ground. The PCB is dual layer with digital ground
plane sections stitched together on both sides where possible. The analog stereo audio output from the
module is buffered by an op-amp stage before sending back to the host system. The analog audio buffer
circuit has a separate power supply and ground system to isolate it from digital noise.
All Bluetooth functionality is controlled by on-board firmware. But the module may be accessed for test
through the SPI port to a computer interface module (available from FreeWings). A description of
specific commands for Bluetooth is beyond the scope of this document and can be found in
documentation from FreeWings or CSR for the CSR8630 chipset.