AM335x Starter Kit (TMDSSK3358) DDR3 schematic issue

pau pajuel

In AM335x Starter Kit (TMDSSK3358) schematic, DDR3 RAM (MT41J128M16JT-125) uses the following configuration in RAM data bus.

Is this configuration correct? or this is a schematic bug?. I attach the actual configuration used in this schematic:

(RAM)->(AM335x)

DQ0->DDR_D3

DQ1->DDR_D6

DQ2->DDR_D5

DQ3->DDR_D7

DQ4->DDR_D2

DQ5->DDR_D0

DQ6->DDR_D4

DQ7->DDR_D1

DQ8->DDR_D11

DQ9->DDR_D8

DQ10->DDR_D14

DQ11->DDR_D12

DQ12->DDR_D15

DQ13->DDR_D10

DQ14->DDR_D13

DQ15->DDR_D9

Thank you for your cooperation.

0160.TMDSSK3358_3H0009_REV1_2B_SCH_PDF.pdf

over 12 years ago

0 Michael Williamson over 12 years ago

Expert 1995 points

I think this is OK, as long as you keep the bits in the same byte group (e.g., keep DDR_D0->DDR_D7 connected to DQ0->DQ7 and DDR_D8->DDR_D15 connected to DQ8->DQ15). If the bits are "scrambled" within the upper or lower byte group the processor / RAM really doesn't care.... We've done this sort of thing to ease routing headaches to DDR parts in the past with no problems...

-Mike

0 pau pajuel over 12 years ago in reply to Michael Williamson

Prodigy 20 points

That's really interesting, i didn't know it.

Thanks

0 Gokul cg over 10 years ago in reply to pau pajuel

Intellectual 420 points

Since the pins are scrambled ,do we need pin-muxing or any driver changed required ?

can I make a custom board with DQ0-DQ7 connected to any of pins in DDR_D0-DDR_D7 and DQ8-DQ15 connected to any of pins in DDR_D8-DDR_D15 without any changes in device driver files if reset of the things kept unchanged ?

Thanks and regards

Gokul CG[gokul.g@kalkitech.in].

0 Biser Gatchev-XID over 10 years ago in reply to Gokul cg

TI__Guru**** 393215 points

Yes, you can. Take note though that DQ0-DQ7 connected to any of pins in DDR_D0-DDR_D7, and DQ8-DQ15 connected to any of pins in DDR_D8-DDR_D15 are the only swaps allowed. Again, no software changes are involved at all for this.

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AM335x Starter Kit (TMDSSK3358) DDR3 schematic issue