I have some problems accessing external memory with the DMA controller of
the C5409 DSP.
I've written a program using the RTDX Interface to read out the memory on my
own protoype board (not a DSK or EVM board).
On this board there is a FLASH ROM and a SRAM memory. The FLASH is located
at address 0x00000 - 0x3FFFF and the SRAM at 0x40000 - 0x7FFFF.
Address A18 is used as a chip select for either FLASH or SRAM.
I'm using the DSP/BIOS Configuration Utility to configure the DMA Controller
for a block transfer of 50 Words from external memory to internal memory.
I've set the SLAXS bit manually in the DMMCR Register and I have configured
the "extended source data page register"
using the DMA_GblConfig structure (e.g. gDMAConfig0.gbldmsrcdp = 0x4 for
But if I call "DMA_globalConfig(0xFFFF, &gDMAConfig0)" nothing happens, the
"extended source data page register" remain unchanged (contains 0x0), even
after some cpu cycles - and therefor address A18 of the DSP is always 0.
Has anyone tried to access to external DATA memory using the DMA Controller?
I've no idea what the problem is, maybe the RTDX affects the Peripheral
(Subbank) Register of the CPU??????
Thanks for any help.