Ettus N200 Connecting to Device

Hi there,

We are considering using a USRP N200 for a project, and want to figure out some technical details before placing the order. We plan to use N200 to control our own device based on the analog RF signal sent from the device.

The general structure is to have the device's output connected to the Rx port of N200. The output signal is processed in N200 and leads to the control (digital) signals which are fed back to tune the device. We plan to use SPI/GPIO ports for the feedback channel. My question is if such SPI/GPIO ports are available on N200? Please note that our device is not a daughter board, so I am not sure if the SPI/GPIO shown on the data sheet of N200 can be used for the control purpose. 

If SPI/GPIO is not available for such control, is there any other connection interface for the control signal sent from N200? Our own device can be relatively flexible, so any connection scheme can be considered.  

Kind regards,

Tom