Connect multiple peripherals to Flexbus (EBI) through FPGA

Thread Starter

guitardenver

Joined Jan 24, 2009
31
Hello,



I have a question about the NXP Flexbus on the Kinetis MCUs. I would like to connect the MCU to an FPGA through a high speed bus that is addressable in the MCU.



I would like to make custom peripherals for the MCU to access and extend the MCU ram and flash. How much support is there for this? Can this be done? I'm only wanted slave devices on the bus.



My question is:

* Is there good HDL support already out there for this? HDL to connect MCU to FPGA and HDL to connect peripherals to the flexbus internal to the FPGA?

* Are there HDL for many peripherals to connect to the bus in the FPGA?

* Is there support for existing Xilinx IP? Specifically all the peripherals that are available for the MicroBlaze?



In my head I'm picturing something like this. Is this what the flexbus is for?



 

Papabravo

Joined Feb 24, 2006
21,159
I am not familiar with FlexBus. I know that when folks tried this with I2C it was an everluvin' freakin' disaster. The FPGA had no equivalent for the bidirectional SDA line, and the operation of the I2C peripherals was sporadic and unreliable. As soon as the pathways through the FPGA were eliminated the I2C peripherals behaved flawlessly. It was done because the hardware engineer believed he could save money and board turns by replacing the two I2C traces with an expensive 208 pin Cyclone II chip. After six failed board turns, he was fired, and on the seventh board turn managed by myself, the product was finally released.

Moral of the story: FPGAs are good for lots of things, but interfacing disparate peripherals on a board is NOT ONE OF THEM!

If you run the interface through the FPGA you will have two things to debug simultaneously. Why undertake that aggravation if you do not have to?
 
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