330 ohm resistors are chosen in order to limit the current flowing through the LEDs to 10mA. The LEDs have a voltage drop of 1.8v.
Therefore there is 3.2v across the resistor (5 - 1.8 = 3.2).
V = IR, which can be rewritten as R = V/I.
Plugging in 10maA as 0.01 gives 3.2 / 0.01 which is 320 ohm. 330 is a close enough value.
|0.01uF Cap (2x)||Bypass caps for level shifters|
|LED (2x)||Battery / Status LEDs|
|330 ohm Resistor (2x)||Current limiting resistors for LEDs|
|Reset Button||Momentary Switch|
|50 Pin Connector||Female Connector to Main Board|