Hi, Thao,
As you know that the SDK2.0 support K66, you can download the SDK2.x from the link:
http://www.nxp.com/ksdk
We have integrated FreeRTOS os in the sdk, pls refer to the example for the freertos:
C:\Freescale\SDK2.0_TWR-K65\boards\twrk65f180m\rtos_examples\freertos_uart
This is the architecture of firmware of the example, In the UART ISR, when the predefined number of data has been received already, the callback functioin is called, the in the callback function, a semaphore is posted, which will have the task to be load/run automatically which is waiting the semaphore.
Hope it can help you
BR
Xiangjun Rong