Look in the reference manual for FSMC, you have the 4 BCRs in FSMC_Bank1->BTCR[0..3] followed by the 4 BTRs, they are not one after the other hence the index has to be 3 and 7 respectively for both cases. FSMC_BANK=6 is actually incorrect, we would have to use #define FSMC_BANK 3 For the correct addressing of BTR4 here, replace: FSMC_Bank1->BTCR[FSMC_BANK+1] = FSMC_BTR1_ADDSET_2 | FSMC_BTR1_ADDSET_0 | FSMC_BTR1_DATAST_2 | FSMC_BTR1_DATAST_0; by 4 Then to configure BCR4, so this line is left as is FSMC_Bank1->BTCR[FSMC_BANK] = FSMC_BCR1_MWID_0 | FSMC_BCR1_WREN | FSMC_BCR1_MBKEN;. That should lead to correct configuration of Bank 4, if all the switches in it are configured correctly. Regards Abhishek
