Lighting apparatus and methods involving a plurality of light-emitting devices configured to emit radiation having at least two different spectra, in which the plurality of light-emitting devices are controlled to produce composite radiation having at least one resulting spectrum that simulates a desired spectrum. An RPC API is described which provides for using an optimized technique and an unoptimized technique for performing RPCs. An offset adjustment circuit receives timing information relating the local clock signal to an incoming data signal and calculates a phase offset and a frequency offset indicative of adjustments to be made to the local clock signal. The display module is mounted in the chamber of the shell.