FMC distrubed when using high speed of LTDC

[fasyr.1]

I'm using STM32H743ZITX for displaying a 1280X720 LCD, first i set FMC frequency to 266 MHz and LTDC frequency to 20, everything was running well and i can read data from SDRAM was same as what i've written to it, but problems come when i set the frequency of LTDC to 64 MHz, when i read data from the SDRAM the datas was being random and didnt same anymore as what i've written before.

could you guys please share your experiece if you have this problem or any suggestion what i have todo?

here i share my clock configuration on STM32CUBEIDE

[KDJEM.1]

Hello @fasyr.1​ ,

According to the datasheet DS12110 and precisely 7.3.17 FMC characteristics Section, for the STM32H743ZIT6 rev V the FMC_SDCLK maximum are:

So try to use a FMC_SDCLK value with respect these conditions.

Please let me know if the problem is solved.

Thank you.

Kaouthar

[fasyr.1]

but i read the other datasheet which is more new revision(rev 😎 below.

it told that the FMC frequency is up to 300 MHz for STM32h743

[KDJEM.1]

Hello @fasyr.1​ ,

Yes you are right, the FMC frequency is up to 300MHz for STM32H743.

But the max FMC_SDCLK we can run SDRAM depends on the VDD and on the capacitor value:

• For 2.7 V<VDD<3.6 V: FMC_SDCLK =110 MHz at 20 pF

• For 1.8 V<VDD<1.9 V: FMC_SDCLK =100 MHz at 20 pF

• For 1.62 V<DD<1.8 V, FMC_SDCLK =100 MHz at 15 pF

Thank you.

Kaouthar