Controlling a circuit board from my PC
You can use serial communication on your board and use an RS232 to USB converter (FTDI) to communicate with the PC.
Also, you can implement serial to USB communication directly on the board using ICs and give a micro usb port output to connect to the computer.
(A UART to USB bridge will be needed, most vendors have those, TI has some, like this). 
Using the FTDI would be easier, but you can design the UART - USB communication, if you're looking for a challenge.