FMC Timing registers can not be written!

[N ORhan]

Im working to use external SDRAM for STM32F746DISCO board and configuring associated FMC register. When ia start to debug i see that all of SDTR (timing) register bits are valued as F. I can write to SDCR and SDCMR registers but can not write to timing registers. What is the reason for that and how can i fix this problem?

Thanks

[Tesla DeLorean]

Having a hard time visualizing this issue, show some configuration code and register view from the debugger.

Review and test the code examples from the repository, and compare-and-contrast with what you are doing.

[N ORhan]

Thank for your answer Clive. i fixed that problem. These register's reset value are 0xFFFFFFFF so when i "ORed (|=)" the register with my values, all of the bits remain as F.