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Observer javichu
Observer
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ZCU104 - PL DDR4 address pins asignment

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Hello,

 

I am using a DDR4 SDRAM (MIG) controller where I defined the following pre-included memory part: MT40A512M8HX-093. The problem is that I get a 17-bit address bus (I suppose the bus width is included in the part definition), but the board uses just 14 bits [A0..A13]. I did not find any option to restrict the address bus to 14 bits so I am wondering what I should do with the upper bits. Should I tie them to ground? I tied them to some FMC pins just to get rid of implementation errors, but I am pretty sure there must be a better solution.

 

Thanks in advance and best regards,

Javichu

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Moderator
Moderator
195 Views

Re: ZCU104 - PL DDR4 address pins asignment

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Hello @javichu,

 

You need all 17-bits of the address bus. A0-A13 are reserved specifically for A0-A13. But A14-A16 will be used for RAS/CAS/WE, specifically in your scenario A14 = WE_N, A15 = CAN_N and A16 = RAS_N. You should not tie these to ground.

 

Thanks,

Cory

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1 Reply
Moderator
Moderator
196 Views

Re: ZCU104 - PL DDR4 address pins asignment

Jump to solution

Hello @javichu,

 

You need all 17-bits of the address bus. A0-A13 are reserved specifically for A0-A13. But A14-A16 will be used for RAS/CAS/WE, specifically in your scenario A14 = WE_N, A15 = CAN_N and A16 = RAS_N. You should not tie these to ground.

 

Thanks,

Cory

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Don’t forget to reply, kudo, and accept as solution.
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