I am working on some project where I need to communicate between two processors (hardware), ATxMEGA128A1 AVR Controller and Blackfin BF522 Digital Signal Processor. Someone help me.
Here, to communicate between a DSP and a UController you can use asynchronous serial link USART that's called as Inter-Processor Communication(IPC). You can code for GPIO pins if you know how to write code for USART,that's available on almost any UController.
In-short you need USART channel to communicate between DSP and UController(IPC).That's the one possible way I don't know about others.