Hi Hello, At this moment Im working on a new project with the NS7520 and a FPGA. What is the correct way to get data from the fpga to the memory with DMA? Is it necessary to use memory to memory mode? Is a buffer necessary? I want to know if somebody has any experience on this subject. Tanks, Joost
I did some better reading of the data sheet, And I’m understanding the Principe of the DMA. The DMA controller will provide the address and needs a latch. The data lines are free to the FPGA. But for the DMA communication port A and/or C are used(some lines). These lines are as far as I understand also used for the serial communication. Do you have to give up one of the serial ports if you want to use DMA or did I miss something?
> What is the correct way to get data from the fpga to the > memory with DMA? Is it necessary to use memory to memory > mode? I’m presuming you will providing some sort of SRAM memory interface in the FPGA… If so, I’ve got a similar arrangement on my HW (NET+50 based). Using an 8-bit wide SRAM memory interface to a CPLD I needed to provide a incoming and outgoing DMA interface for an I2S Audio codec… I must admit I found the DMA sections in the datasheets very hard to understand at the time… in the end, after reading the many errata items to do with external DMAs, I designed the board to use the mode that does the transfer as two bus operations. i.e. CPLD -> Net+50 -> external memory (SDRAM). However, the project was cancelled before the software was written to test out if it works… Regards, Dave
When you have the external DMA channels enabled, I think you can still use both UARTs as long as you don’t want both sets of RS232 HW flow control signals… from recollection you lose the DSR, DTR and DCD lines from a UART if the DMA lines are used… Regards Dave