What is the advantage of Crossbar Switch

[arthivenkatasub]

Hi All,

I want to learn about the advantages of XBAR in MPC5643L. Why we need crossbar for controller?As we have interrupt priority in other controllers like MC9S12XE and MC9S12XHY, why there is need for master slave concept?Also I heard that it is enough to have default configuration for XBAR in MPC5643L. Then what is there to do with XBAR? I didnt get these things? Is crossbar switch is advangeous for MPC5643L? I need the exact answers for the above questions.

Regards,

Arthi 

[davidtosenovjan]

The crossbar switch allows both the DMA (or other master) and the core to access the bus slaves simultaneously, this greatly speeds up execution time and performance. Note the DMA (or other master) and the core cannot access the same peripheral at the same time an arbitration scheme is in place to take care of this instance should it occur. It has nothing to do with interrupts or interrupt controller, XBAR is a crossway of internal busses (data and instructions).

It is quite common to leave XBAR setting untouched, but it may happen in certain situations that changing priorities is necessary, for instance if one master (core 0) continuously accessing certain slave and other master (core 1) cannot get free time slot to access the same slave. For example, choosing of round-robin arbitration scheme would solve this issue and both cores would have equal chance to access the slave.

XBAR is a base of all MPC5xxx devices.