Changing DDR topology from 64 bits to 32 bits on TMDXEVM6678L EVM

Jean-Michel,

Are you planning on using 2 32-bit memories and using it in 64bit mode.  Or are you planning on using it in 32 or 16bit mode?

For 64bit mode, you'll have to use the full set of memories on the board.  That said, I'm not sure what you'd be expecting to find that is different. 

Please provide more details about what you'd plan to implement and what you suspect may act differently.

Best Regards,

Chad

Hi Chad,

The EVM board use 64 bits configuration using 4 DDR3 (+ 1 reserved for ECC). To reduce consumption, we plan to make our design with only 2 DDR3.

To evaluate the impact, I try to configure the EVM to do this.

I have finally found this configuration is in the SDCFG register (bit NM = 1 instead of 0) from DDR3 Memory Controller.

I suppose that using  a gel file with this configuration, I will be OK. is it correct ?

For the moment, I try to get the GEL configuration operating in my project:

- I have duplicated the evmc6678l.gel provided.

- In my .ccxml configuration, I have indicated to the processor 0 to use the gel file (Initialisation script) but I'm not  yet sur if it runs.

- I expected to have something in the Gel files window but I see nothing special.

Jean-Michel,

This really didn't address me question.  DDR3 memories come in 8bit, 16bit and 32bit wide modules.  You can implement a 64bit DDR3 interface w/ only 2 DDR3 chips, this you'd not be able to represent on the EVM.  You could also limit it to being a 32bit DDR interfaceusing 2 16bit DDR3 memories.  This I believe you could do with the EVM by programming the DDR3 interface to being a 32bit mode and the DSP would only be using 2 of the DDR3s.  That said it would not be representative of the performance of using 2 32bit devices for a 64bit DDR3 interface.

Best Regards,

Chad