STM32F427 FMC DMA vs STM32F407 FSMC DMA

cpinkstone2 · ‎2014-03-31

Posted on March 31, 2014 at 12:49

Dear All,

I've recently upgraded the CPU on a product using a 407 device, to a 427 device.

We are using the DMA2, in memory to memory mode, to write from external SRAM to a display controller also on the external bus.

On the old 407 chip the DMA worked fine, outputting graphics to the display, no problem.

With the new 427 chip I can transfer from external RAM to the display without using DMA so I'm sure my FMC bus setup is fine.

Also I'm running both chips at 168MHz so no change in the clock rate.

If I use the DMA I get corrupted data on the screen. Is there a difference in the DMA between the 2 chips? Should the FMC bus timing be different if using DMA?

Thanks for any help given.

#dma-stm32f427-fmc

waclawek.jan · ‎2014-03-31

Posted on March 31, 2014 at 12:59

My guess is that you see the write FIFO buffering in FMC in action. I would start with checking the timing with an oscilloscope, and setting BUSTURN to nonzero.

JW