On platforms with an on-board status LED, the LED will be lit or blinking when the device first initializes. The light will turn off when the user opens the device and begins communication. From this point onward the status lights are under user control.
# Pin Configuration
When uOSC starts for the first time, all pins are configured as inputs. If a pin is not connected to something (e.g. ground, or a sensor), then it is a _floating input_. Floating pins may spontaneously accumulate charge in response to all sorts of things including capacitance with your finger, etc. Floating analog inputs may appear to have some non-zero value that changes. Floating digital inputs may spontaneously change between 0 and 1. You can ignore floating inputs, or you can ground them which will explicitly force them to zero.
# Power Utilization
The limit for power utilization is 100mA during initialization and then increases to 500mA after the device is enumerated and configured by the host. If your circuit uses a lot of power then it may be a bad idea to draw that power from the microprocessor anyways because it will cause the chip to heat up. In this case power from an external supply should be switch with a transistor.
# USB Voltage
USB bus power provides a nominal 5 volt source. However, this voltage will vary considerably over 4-5 volts depending on what is providing the power (e.g., laptop computer, desktop computer, unpowered hub, powered hub). If the circuit requires a precise voltage, use a voltage regulator, or an external power source. It may be desirable to set the analog inputs to use ratiometric conversion against the reference voltage (Vref).
