C6748 Unused DDR_A[13] Connection

Daisuke Maeda

Guru 20455 points

DDR2 memory device does not have A[13], but has RFU (Reserved for future use).

Where should DDR_A[13] connect to? Can it be unconnected and be left?

The DDR_A[13] connects to RFU in the TMDXLCDK138 board. Can it connect to the RFU?

Best regards,

Daisuke

over 11 years ago

0 Senthilkumar Srinivasan over 11 years ago

TI__Mastermind 43660 points

Hello Daisuke,

The C6748 device supports DDR2 SDRAM up to 256MB. The DDR2 memory device with 64M16 configuration has A[0:12] address lines and 128M16 configuration has A[0:13] address lines. The pin R8 (RFU) of 64M16 device matches with the R8 pin (A13) of 128M16 device when you match the pin-out.

In LCDK board, we mounted 64M16 device in the board and also provided an option to mount 128M16 device.

If you are designing with 64M16 device and no plan for higher density, then you do not need to connect A13 to R8 pin (RFU) of 64M16 memory device.

Regards,

Senthil

0 Senthilkumar Srinivasan over 11 years ago in reply to Senthilkumar Srinivasan

TI__Mastermind 43660 points

Hello Daisuke,

The above post is edited for change in configuration.

Regards,

Senthil

0 Daisuke Maeda over 11 years ago in reply to Senthilkumar Srinivasan

Guru 20455 points

Hi Senthil,

Thank you for your reply.

If connecting DDR_A[13] to RFU is not needed, can DDR_A[13] be left floating?

Best regards,

Daisuke

0 Senthilkumar Srinivasan over 11 years ago in reply to Daisuke Maeda

TI__Mastermind 43660 points

Hello Daisuke,

Yes, you can leave the A13 pin unconnected when you are using 64M16 memory device.

Regards,
Senthil

0 Daisuke Maeda over 11 years ago in reply to Senthilkumar Srinivasan

Guru 20455 points

Hi Senthil,

Thank you for your reply.

I have a similar question.

A 32M16 (4 banks) memory device does not have BA[2], but has RFU. Can this device be used?

If so, can DDR_BA[2] connect to the RFU? If connecting it to RFU is not needed, can it be left floating?

Best regards,

Daisuke

0 Senthilkumar Srinivasan over 11 years ago in reply to Daisuke Maeda

TI__Mastermind 43660 points

Hello Daisuke,

The C6748 device supports the memory device with 4 internal banks. The DDR_BA[2] connection to the RFU is based on your requirement. If you intend to change the memory in future to 8 banks, this connection is needed. If not you can leave this connection and the DDR_BA[2] can be left floated.

Regards,

Senthil

0 Daisuke Maeda over 11 years ago in reply to Senthilkumar Srinivasan

Guru 20455 points

Hi Senthil,

Thank you for your reply.

Best regards,

Daisuke

0 PhilM5 over 10 years ago in reply to Senthilkumar Srinivasan

TI__Intellectual 1680 points

Hi Senthil,

I have a case where the memory device needs to have the A[13] I/O connected to 0 for good operation.

Can you please confirm what the operational value of the DDR_A[13] would be if connected to a physical memory device? will it remain always ZERO ?

as a remainder the OMAP L-138 datasheet does not explicitelly describe the DDR_A[13] , see Table 15-12 and Table 15-13 about MRS and EMRS commands issues by the controller.

Thanks for elaborating.

Cheers

0 Senthilkumar Srinivasan over 10 years ago in reply to PhilM5

TI__Mastermind 43660 points

Hello Phil,

The requirement of A[13] pin depends on the DDR memory capacity as i mentioned in the earlier post. What is the memory capacity of the device you are using ? Rather what is the part number of the device ?

If you connect the A[13] pin to the memory device, then the operational level would be based on the memory location that you are accessing. It is not necessary to be always 0.

Regards,
Senthil

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C6748 Unused DDR_A[13] Connection