Hi Rob,

My first advise would be to relax your demand for an 11.059 MHz crystal. This will be an excellent exercise in engineering. You need to use one crystal that will produce an acceptable baud rate for your UART, and also provide accurate timer steps for producing a 40 kHz output. First, read the tutorials on this site. They can be found on the navigation bar to the left. Pay particular attention to the use of timers and the UART (obviously). Once you have a handle on how to do the necessary calculations, determine which crystal frequencies will give you the 40 kHz period you need, within whatever % error you can tolerate, and then see which baud rates you can produce with each of those frequencies. Choose the one that leaves you with the most choices. I suggest doing this on a spreadsheet.

Someone correct me if I am wrong about this, but isn't it the case that the UART can pretty much handle 3% error in the baud rate? I think that's right. Anyway Rob, you might do a search of this site, and maybe on Google too, to see what you can learn.

Finally, you will want, make that need, to read the Bible from Philips. Erik Malund will give you the links (it's kind of his job on the forum), or you can do a search of the forum for "Bible" and you will find them posted in something approaching a myriad threads.

Good luck.