hey guys I have been working on a project to teach the MSP430g2553 to talk over low speed USB (like the AtMel chips can) the circuit basically takes the SPI in and out pins and converts is to incoming and outgoing for the differential USB signal, and also detects / sends the Single ended zero’s I need to. The circuit itself works, but this is the first board I have ever done (just got eagle light a few weeks ago).
I am sure there are things I could do better or are just doing plain wrong. the board is 20mm square, double sided. This is a Photoshop composite of the Gerber files for the layer / stop / silk screen showing front and back, with and without silk screen.
http://www.woodrell.com/joe/msp430/boardV1-2b.jpg
http://www.woodrell.com/joe/msp430/boardV1-2_schemb.jpg
the parts list
U1: ESD / Edge Rate - STF203-33
U2: Transmit Signal DPDT - TS3USB30
U3: NOR to detect incoming SE0 - 74LVC1G02
U4: Buffer to disconnect recieve pin when transmitting - 74LVC1G17
R1: Shield to Ground - 33K ohm
R2: ZD1 supply Resistor - 47 ohm
ZD1: 3.6V Zener Diode
SD1: Shottky Diode for 5V short protection
SD2:Shottky Diode for 5V short protection
X1: USB mini-B plug
JP1: Power out to MSP430
JP2: Signals to and from MSP430
JP3: Jumper to allow USB to provide power, or not
the board passes the DRC for Seeed Fusion service (their DRC file).
Thanks for any input or improvements you guys can suggest.