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FlexBus Chip Selects Not Routed To Pins

Question asked by gcary on Oct 14, 2014
Latest reply on Oct 20, 2014 by xiangjun.rong

I'm having difficulty squeezing in all of the peripherals I need into a K60 design.  I am using the FlexBus, which consumes a lot of pins.  I'm down to just a couple of pins that have conflicting assignments.  Do FlexBus chip selects need to be routed to a pin?  I don't need a chip select pin because the FlexBus is interfacing to an FPGA.  The FPGA will decode the address and know how to behave, so it doesn't need the chip select.  I need 2 chip selects because I will have two functions in the FPGA and each will have different timings.  Chip selects control a number of FlexBus parameters, such as wait states, port size, Byte-lane shift, etc.


Please correct me if I'm wrong about not needing the chip select signal.  ALE signifies the start of a cycle.  After one word is written in a write cycle, the FPGA will end the cycle internally and begin look for ALE to be asserted again.  For read cycles, the OE_n signal has the same timing as the chip select.  So no chip select is needed for reading or writing. All of the transfers will be single-word.