Placing a bypass capacitor on an LCD w/built-in serial controller a good idea?
There is no need for any bypass capacitor.And you don't confuse the bypass capacitors and a stabilizing capacitor(capacitor connected parallel with power supply).Bypass capacitors are generally used in amplifier circuits.Basically,to provide a low resistance path for an AC signal,bypass capacitors are used.From the capacitor impedance z=1/(2*pi fC),you can notice that ,if frequency increases,impedance decreases.In general,they're used inbetween the input and output for low resistance path.But the stabilizing capacitor is used to maintain the voltage almost constantly and reject the sudden changes occur in the power supply unit,so that you're LCD will be safe for peak shoots of voltages.So you don't need to use a bypass capacitor,but you can use stabilizing capacitor