Kinetis Flexbus External Flash and RAM

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Kinetis Flexbus External Flash and RAM

Contributor IV

I have some questions about the flexbus on the Kinetis devices.

1) What kinds of flash memory are supported on the Flexbus. I read NAND flash is not recommended.

2) Can you write to external Flash via the flexbus interface? Or do you have to write the chip via JTAG?

3) Can you use a debugger that is connected to the Kinetis MCU to write to external flash and/or RAM? For example, can I specify a const array with a C attribute specifying an address that is external FLASH or RAM and have the debugger work like it was internal ram or flash? I would like to load large C arrays to external flash.

4) What debuggers support writing to external flash and/or ram?

5) Can I make a section in the linker file and have a C array attribute telling it to go to that linker section for external flash address?

6) Any recommendations on how to connect external flash and RAM as seamless as possible?

7) What are the best development boards with Kinetis devices that would help with learning how to connect external flash and ram via flexbus?

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NXP TechSupport
NXP TechSupport

Hi, Matt,

As you know that you can connect external NOR flash, SRAM or the memory-mapped device to FlexBUS interface, obviously, you can not connect NAND flash to FlexBus interface, NAND flash need special  interface.

You can develop code to write constant data to flash via FlexBus, firstly, you should connect the NOR flash to FlexBus of the Kinetis processor, from software perspective, you should initialize the FlexBus register so that the Flexbus can generate the timing to access flash when your read/write data from/to flash. The NOR flash does not have JTAG pto flash, it is impossible to write data to flash via jtag, I suppose you can not write constant data to flash using tools by just modifying link file, because the NOR flash needs to write key words to specific address. so firstly, initialize FlexBus register, secondly, write key words to specific flash address, thirdly, write constant to flash one by one.

You can order the TWR-MEM board to evaluate how to write SRAM or Flash, on the board, there is MRAM.

Memory Tower System Module|NXP 

I suppose that you can use TWR-K64F board and have a try.

Hope it can help you


XiangJun Rong

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