1723 - CPRI: Can Lattice CPRI IP core (Common Public Radio Interface) support auto-negotiation?
Lattice CPRI IP core (Common Public Radio Interface) itself provides the auto-negotiation function. There is a state machine that will automatically go through a searching state from one line rate to the next line rate, eventually it will find the line frame and stay at the appropriate line rate to establish the link. But since the IP core itself is not a completely independent solution, it has to be implemented with SERDES/PCS, the core itself does not have controlled function to reconfigure the SERDES/PCS line rate setting. Thus, the Lattice CPRI IP core itself does not provide the complete solution for auto-negotiation.
For applications that requires the auto-negotiation function, there is a solution. The SERDES/PCS line rate reconfiguration needs to be done at the system level via software, meaning that system user will have to implement software from the system level and perform a hard reconfiguration on the PCS/SERDES to the appropriate line rate that matches the far end transmitting data rate. From there the Lattice CPRI IP core can then handle the line rate negotiation to handle the data processing inside of the core.