BeagleBord with Microcontrollers

Hi,

Is there anyway that a beagleboard can be connected to a
microcontroller such as XC167?

yes

I could report my experience with atmel AVR uControllers...
You can make two devices communicate using beagleboad expansion
connector, enabling an additional UART or an SPI port..
You have to level-shift you signals (if XC167 is not powered at 1.8V
which a don't know) because expansion connector tolerate only 1.8V
(you will destroy you beagleboard if you connect an higher voltage to
it). Look for example at TI's TSX0108 level shifter...

For the software point of view, on the beagleboard side you have just
a file (/dev/ttyS2 or /dev/spidev) to handle (it's UNIX 'everything is
a file' abstraction here), on the uController side it's up to you
playing with your device registers..

  j