DDR interfacing with AM1705

gaurav powar

Other Parts Discussed in Thread: AM1705, AM1707

I am designing AM1705 dev. board. I am confused in DDR interfacing. i have to interface 128 MB DDR with AM1705 but i am unable to do it. please help me for how can i interface 128MB DDR. I able only 64MB DDR to AM1705

Secondly i have to interface both NAND flash and SD card and pins are multiplex so how can i do it.

over 8 years ago

0 Senthilkumar Srinivasan over 8 years ago

TI__Mastermind 43660 points

Hello Gaurav,

Are you using DDR or SDRAM in your design ? The AM1705 device does not support DDR, it only supports SDRAM upto 128MB memory space. Please refer device data manual and TRM for more details.

You cannot access both NAND flash and SD card at the same instant as both the signals are multiplexed. You may need to have external logic to access one part and completely isolate the other one. What is the purpose of the NAND flash in your design ?

Regards,
Senthil

0 gaurav powar over 8 years ago in reply to Senthilkumar Srinivasan

Prodigy 70 points

hi,
thank you for reply
can you suggest any SDRAM ic and external logic for demultiplexing NAND flash and SD card

0 gaurav powar over 8 years ago in reply to gaurav powar

Prodigy 70 points

hi,
my problem is AM1705 have A0-A12 address line and if i select 512Mb(32MbX16)SDRAM then it have same amount of address line A0-A12 so how can i connect two 512Mb(64MB) SDRAM to make it 128MB SDRAM

0 Senthilkumar Srinivasan over 8 years ago in reply to gaurav powar

TI__Mastermind 43660 points

Hello Gaurav,

There is no specific recommendation on SDRAM part. However you could refer the AM1707 EVM design in which 256Mb SDRAM parts are used. The address lines mapping for various memory capacity are available in the device data manual table 6.20 and TRM table 20.4.

www.ti.com/.../am1707.pdf

www.ti.com/.../spruh94b.pdf

Regarding de-multiplexer part selection, you could chose a part from the following link based on your requirement.

www.ti.com/.../multiplexer-demultiplexer-products.page

Regards,
Senthil

0 gaurav powar over 8 years ago in reply to Senthilkumar Srinivasan

Prodigy 70 points

which signal pin of am1705 i suppose to use for demultiplex NAND flash and SD card signal

0 Senthilkumar Srinivasan over 8 years ago in reply to gaurav powar

TI__Mastermind 43660 points

Hello Gaurav,

You can use any GPIO to select the NAND or SD card path.

Regards,
Senthil

0 gaurav powar over 8 years ago in reply to gaurav powar

Prodigy 70 points

hi,
i am giving simple example suppose i have to connect two 64MB SDRAM then how can i connect address pin
please i am not understanding memory mapping due to i found same address line of AM1705 and 64MB SDRAM
please help me

0 Senthilkumar Srinivasan over 8 years ago in reply to gaurav powar

TI__Mastermind 43660 points

Hello Gaurav,

Assume you have A[0:12] and D[0:7] in your 64MB SDRAM, you have to connect EMIFB A[0:12] address lines to both the SDRAMs and EMIFB D[0:7] to one SDRAM and EMIFB D[8:15] to the other one.

Still you want to know some basic understanding of interfacing the SDRAM, please surf on the internet where you could get lot of tutorials or you may seek for guidance from your senior officials.

Thanks for your understanding.

Regards,
Senthil

0 gaurav powar over 8 years ago in reply to Senthilkumar Srinivasan

Prodigy 70 points

thank you for support. i was only thinking about A[0:12]and D[0:15] SDRAM

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DDR interfacing with AM1705