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Change VTT Regulator

Eric Cheng1
Intellectual 320 points

Hi Sirs, 

The reference design of the DDR VTT_Regulator pin.The EVM-SK uses the GPIO0_7. In our custom board, we change the pin to GPIO3_16 due to the HW layout placement. Is there any problem about this change for the suspend/resume?

we are tracing source code of  sleep33xx.S and checking the TRM. It only defined the GPIO0 as one of the L4_WKUP peripherals, but none of GPIO1~3 as the member of L4_WKUP peripherals.

The key question is it proper for stanby issue since we changed GPIO0_7 to GPIO3_16 as DDR VTT_Gen pin?(aka CKE of DDR)

Thanks for your reply.

 

 

 

  • 0
    TI__Guru**** 393215 points

    Hi Eric,

    On the Starter Kit GPIO0_7 is used as an output for controlling the enable signal of the Vtt regulator. Suspend maps to DeepSleep0 power mode on the AM335X. In this mode only the PD_WKUP power domain is on. Therefore GPIO3_16 will not be powered (you are right that only GPIO0 is on the PD_WKUP power domain).