Two main emphasis of this board are USB and Serial as well as using socketed components. The 28-pin PIC24FJ64GB002 can perform as either a USB host or USB device, using jumpers to select between the connected USB socket. The USB jumpers are also configured so when the PIC is USB host using the USB-A connector to attach a thumb drive, the USB-B connector may be configured to attach to an FTDI FT232RL chip to act as USB serial. Using a USB-A to USB-B adapter, both the PIC and the FTDI chips could be active as USB devices.
Two serial channels are jumpered for either RS-485 or RS-232 (DB-9 connectors not shown), or the second serial channel can be jumpered to the FTDI USB serial connection. As configured here, RS-485 uses RX/TX with RTS to select whether reading or writing. RS-232 can use RX/TX with CTS/RTS. The ICSP (in circuit serial programming) connection in the lower left works with ICD or PICKit programmers, and shares the lines that provide CTS/RTS, so jumpers are provided to choose between those functions. The PIC24 has quite a few 5V tolerant inputs, but I ran out of enough of them, so a 5V/3V3 logic level conversion board is socketed to read the CTS lines at 3.3V from the 5V MAX232 and MAX233.
Voltage regulators are included to power 3.3V and 5V buses, accepting power from USB or 7V-12V external power. Each module has a power jumper to effectively disable them. The USB sockets have jumpers to selectively attach power to the 5V bus.
One SPI channel is also configured, allowing connection of features such as a micro SD card and/or SPI Ethernet. This board specifically supports connection of a Microchip's PICtail Ethernet (ENC28J60) board.
