Serial port

There is an in-depth article covering several Samsung devices in the SamsungSerial page

Settings

Device I/O voltage ID<->GND SOC TX SOC RX switch Comments
I9300 1.8V (measured between USB GND and USB VCC) 619kOhms D- D+ It gives a shell once Replicant has booted
Nexus S 150 kOhm FSA9480
Galaxy Nexus
Optimus Black