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External SDRAM bank selection on LPC407x

Question asked by Otavio Borges on Jul 3, 2017
Latest reply on Jul 4, 2017 by Carlos_Mendoza



I'm currently developing an application using LPC4078FBD208 that will use 3 external AS4C4M16S SDRAM ICs from Alliance.

I've been following AN10950 to perform connections between SDRAM and MCU. Example from Fig. 5 on the AN is the most similar with my SDRAM IC pinout. But I have a question on the Address Bus.

I noticed that MCU pins EMC_A[0:23] have been connected to memory address bus and the two bank pins to EMC_A13 and EMC_A14.

My doubt exactly is why EMC_A12 was skipped (A11 from SDRAM is connected to EMC_A11 but BA0 was connected to EMC_A13). There's a particular reason from that? This example is for LPC24XX family but is directly applicable to LPC407x family?