This is a PCB for a Synapse Wireless RF200 module. It provides access to 2 relays and 4 GPIO pins of the module. There are 2 status LEDs as well. It can also provide a usb port to allow a computer to communicate to the module. 

Power can be provided by a mini-USB plug or via 2 pin screw terminal.

Relay0: set GPIO0 high
Relay1: set GPIO1 high

LED0: set GPIO5 high
LED1: set GPIO6 high

There are 4 ways to power the board:

1 - FTDI Power via USB cable
 Populate IC1, C2, C5, R6

2 - LM317 Power via USB cable
 Populate U1, R2, R3, R4

3 - LM317 via screw terminal
 Populate U1, R2, R3, JP2 

4 - Regulated 3.3V
 Populate JP4, R4


R4 and R6 allow you to swtich the power source even if the other parts are populated. 

For power options 2-3 you can provide 3.3V to JP4 for external use by populating R4. 

Note that the FTDI chip can only supply enough current for the module, so you won't be able to use it to power external devices.