I am new to schematic design and studying OLinuXino A10s schematics. A generic question :
How do we decide the resistor & capacitor values required to interface multiple ICs on a pcb ?
E.x. I am unable to understand why a 22ohm resistor is present in the clock signal (SCK,SCK# pins - W2, Y1 ) from A10s to SDRAM (h5tq2g83cfr-h9c) (CK, CK# pins - F7, G7). It is not given in either of their datasheets.