VF5xx / combination of NAND I/F and External bus

[soichiyamamoto]

Hi,

Is the combination of NAND I/F and External bus possible?

Best regards,

soichi yamamoto

[naoumgitnik]

Dear Yamamoto,

May you provide more details of your application, please? - How would you like to combine these 2 buses?

Regards, Naoum Gitnik.

[soichiyamamoto]

Dear Naoum Gitnik,

Thank you very much for your help.

But  pin of flexbus I/F and NAND Flash I/F use the same pin.

My Application use flexbus for FPGA.

And I want to use NAND Flash memory.

This is a tough question.

Best Regards,

soichi yamamoto

[anthony_huereca · Accepted solution]

Hi Soichi,

  While there are many mux overlaps between the Flexbus and NAND, it would be possible to only use the lower 16-bits of the Flexbus which are not muxed with the NAND pins. And as long as you aren't using some of the optional Flexbus pin options (like TSIZn, BEn, etc), sharing the NAND and Flexbus might be possible in your application. The TWR-LCD only uses FB_RW and FB_CS for instance, so depending on what you need for your FPGA, this work-around may work for you.

  The main thing to keep in consideration is that FB_OE and NF_RE are muxed on the same pin, and that is a commonly used signal on the MRAM and other devices.

  The reason the Flexbus wasn't brought out on the Vybrid tower board was because those lower Flexbus pins are muxed with the QuadSPI pins, and that was a higher priority on the tower board to preserve signal quality.

-Anthony

[naoumgitnik]

Dear Yamamoto,

Thanks, it is clear now.

Unfortunately, there is no other way to share the same processor's pins among several peripheral devices than using chip selects for each of them and reconfiguring the shared processor's pins every time you switch a peripheral device.

Not elegant, not easy from the software point of view + this switching takes time and slows the system operation speed down.

I would only do that if had no other choice or if turning to the NAND FLASH was quite infrequent.

Regards, Naoum Gitnik.