STM32H743 triggers multiple NWE for single write in FMC

utku · ‎2026-01-16

Im trying to drive 3.5 inch TFT LCD with STM32H743 using FMC. My setup is :

ChipSelect: NE1
Memory Type: LCD Interface
LCD Register Select: A18
Data: 8 Bits

My timing settings are (FMC Clock: 10Mhz):

Address setup time in FMC clock: 3
Data setup time in FMC clock: 2
Bus Turn around time in FMC clock: 2

Here are the parts of code:

#define FMC_BASE ((uint32_t)0x60000000)
#define LCD_CMD (*((volatile uint32_t *)(FMC_BASE)))
#define LCD_DATA (*((volatile uint32_t *)(FMC_BASE | (1 << 18))))

When I try to write a data, as shown in the attachment, my logic analyzer shows me multiple WR event occured and shows some weird signals on data line (D0-D3).

I do not understand where I did wrong...

mƎALLEm · ‎2026-01-17

Hello,

To drive LCDs through FMC with MCUs with Cortex-M7 you need to configure the LCD memory region in Strongly-Ordered or Device configuration using the MPU.

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