Need help about bus problem in designing board for stm32f407vgt6

[dionisiusdani]

Posted on April 15, 2015 at 09:36

i am going to use 16 bit wide data bus in high speed (roughly 20mhz). so theoretically, i need to use one port? the problem is the lqfp100 package that the chip has, have all the port pins scattered. none of the port have sequential pins on the package. i am going to use sdio and dac, so i can't use portC, port D and port A. am i correct?

moreover, i guess i need to route the trace to the pins in same length, even the port pins are scattered? any advice?

Thank you.

[Tesla DeLorean]

Posted on April 15, 2015 at 19:26

As GPIO or FSMC?

Common length is more critical for SDRAM. Reasonably similar should suffice for 20 MHz

If you're attempting to DMA to GPIO at 20 MHz rates, then yes you want to commit the whole bank together to get the signals aligned. For an FPGA type interface use FSMC.

Escaping pins/peripherals on the STM32 is a mind opening exercise.

I think Micro Xplorer and Cube offer some fitting functionality, but 100 pin devices will be a challenge.

[dionisiusdani]

Posted on April 16, 2015 at 02:01

yes, i am going to use dma for that data bus. i am using level converter to interface 5v data bus (lcx245). should the DIR pin connected to an alternate function pin or any pins ok? is it in dma configuration?

Thank you for your help.

[dionisiusdani]

Posted on April 16, 2015 at 02:27

my mistake, i've just realized dma established to be one direction.