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Associate III

Hi, I'm using STM32H750-DK as an example to build my board. And I don’t know for what purpose resistors R121 - R158 are installed. Can I directly connect these pins to ground?Screenshot_4.png

ST Employee

Welcome @Denys_T, to the community!

The SDRAM is a 32-bit type in which only 16 of the 32 data lines are used. However, as these data lines are bidirectional and can also be outputs, a pull resistor must be connected there.

Hope that answers your question?


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>>Can I directly connect these pins to ground?

No, and not to each other either.

The 10K pull-down just terminates the unused input/output pins of the memory.

Uses half the device likely as a cost saving, or inventory reduction method. Might have a longer availability window or guaranteed form-n-function replacement in the future.

32-bit not used to reduce pin-count, escape or availability.

32-bit would be better for higher bandwidth / lower contention.

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