I have the AT91sam7se512 do a SPI DMA transfer from the an ADC. SPeed is 1MS/s. Each sample is 16bit. So 16Mbits/s.

If I use the internal SRAM as the buffer, there is no issue. Once I enable the SDRAM and still use the internal SRAM, I start to have garbage data.
If I move the buffer to external SDRAM, I still get garbage data.

I wonder if there is a known issue with DMA with external SDRAM on AT91sam7SE family chips?

thank you.

hello,
that's a known bug.
take a look at the datasheet, chapter 43.2.5.1 SDRAMC: PDC Buffer in 16-bit SDRAM while the Core Accesses SDRAM.

regards
gerhard