RTOS/CC2640R2F: i want use a GPIO pin to provide 3.3V to a periperal child board how can i realize it

Part Number:CC2640R2F

Tool/software:TI-RTOS

i want to use a free GPIO pin in the CC2640R2F launchpad xl board to provide a 3V-3.3V to a peripheral connected to which,

does the GPIO can be configured to fulfill this function ,if so ,how can i set the GPIO, 

i meat to use the GPIO to power on  the childboard and use delay_ms() funciton keep some time than power off.

i have learn about the borad has a free 3.3V  pin. but i can not customize it to power on or off with out manually plug in or plug out.

can some experts give some tips , thanks a lot!