I'm using the STM32F746G-Discovery board which has an external 8MByte SDRAM. I've made tests to read the SDRAM by testing to access it by declaring:
float *testvar = (float*)0xC0000000;
*testvar = 3.4f;
In my experiments it appears as if the reading that variable is about half the speed as if it was declared in the internal RAM. Is it possible to tweak the clock to the SDRAM to get performance comparable to the internal RAM?
Also is there an attribute command to tell the compiler to place a specific variable or vector in the SDRAM without having to specify the address manually?