[quote user="Rex Chang"]
Steve,
ARM accesses DDR3A memory and DSP mem_reserve on DDR3A and DDR3B which is 2GB. Please refer to either the schematics or TRM at http://www.advantech.com/Support/TI-EVM/EVMK2HX_sd.aspx.
Rex
[/quote]
Hi Rex:
Rex:
In the post Last week above,you said that ARM accesses DDR3A memory and DSP mem_reserve on DDR3A and DDR3B.But I felt it maybe not right when I looked into the tci6638k2k datasheet_SPRS836A.
From pic1,we know that :
This region is mapped to DDR3A or DDR3B depending on the state of DDR3A_REMAP_EN pin at boot time. If the pin is ‘1’, this region is mapped to the first 2GB of DDR3A
which is aliased of 08 0000 0000 to 08 7FFF FFFF. If the pin is ‘0’, this region is mapped as 2GB of DDR3B.
That means the region on ARM is mapped to DDR3A or DDR3B. it depends the DDR3A_REMAP_EN. Another also from the pic1,we see the region on DSP is definitely mapped to DDR3B.
About DDR3A_REMAP_EN, I looked into the K2H_K2EVM-HK_SCH_A102_Rev1_0.pdf from www.advantech.com .From pic2,I can see that DDR3A_REMAP_EN was pull down on boot up.So DDR3A_REMAP_EN = 0 on 6638 starting.So it means that the region 0x8000 0000 to 0xffff ffff is mapped to DDR3B.
So,it is very different with what you said ARM accesses DDR3A memory .
Another from pic3,We know that the size of DDR3A is 2GB DDR3 DIMM ,But only 1GB could be accessed by ARM as last week you said because of bus issue. And for DDR3B,There are five SAMSUNG_K4B2G1646E-BCK. Every chip is 256MB.Excluding the chip use for ECC.Only 4x256MB = 1GB can be accessed.
So Rex, Do you think you view wright or wrong? On the earth ,DDR3A can be used for ARM or DSP? Also DDR3B can be used for ARM or DSP? What’s your opinion?
pic1:
pic2:
pic3:
