Hi Kameltej,
Freescale does not have a ZigBee chip with "everything" inside. you need our development tools to put in the software needed.
I would recommend that you go look for a ZigBee module as these can come with a UART interface that you can use.
E.g Maxstream has modules you can buy via Digi that has a uart interface.
You can look at our ZigBee partner weside and check out all the partners:
BR,
Mads