Whilst you haven't told us how the micro controls the lights, I'm assuming you can't do 16 channels of phase control and DMX512 on a 8052 without extra hardware or some pca's. Anyway, with a 16mhz 8051/2 you can do dmx512 easily but won't have too much processing left. See the code library for a link to a site which has some dmx code. To get the required speed you need to think very carefully about each instruction and count the cycles. 'Dirty' code is required here! Don't expect to do it in 'c' unless you have a souped up 8051/2 style cpu. You have less than 44uS to process
the incoming data and get out of the interrupt - the faster you can do this, the more cpu time is left over for other things.

Many years ago I did a dmx demux to 0-10v for 64 chans with a 16mhz part -no probs.