Notes on using the HCS12 interrupt driven SCI (UART).
=====================================================
By Colin D. Bennett, 13 May 2008.

Interrupt driven UART I/O is broken on the MC9S12DP256 microcontroller,
which is the microcontroller on the Dragon12-Plus board. 

* Important Note! *
*   Interrupt driven SCI communications is broken on the MC9S12DP256,
*   which is the MCU used on the Dragon12-Plus board. See:
*
*     Freescale Engineering Bulletin EB614/D: 
*     SCI Interrupt Errate Workaround for HCS12 Family Devices.
*
*   This bulletin does detail a nasty workaround that uses the HC12
*   timer to generate periodic interrupts to get around the bug, 
*   but in my opinion it is not worth the hassle of dealing with.


