Hello @ikhwan-affan
In the STM32H755BITx , the unmuxed memory connections requires number of address lines (FMC_Ax) as shown below

In STM32H755ZITx (LQFP144 package) , the unmuxed connections are not supported in this package, because there are not enough available pins to expose all the necessary address lines as shown below from DS12919 Rev 2

(FMC_Ax) are not available as physical pins in LQFP144 package
THX
Ghofrane
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