Phantomix

What happens with the adress when you access any kind of memory? let's have a look Reading/writing 8 Bytes from a memory address: A0 A1 A2 A3 ... 0 0 0 0 1 0 0 0 0 1 0 0 1 1 0 0 0 0 1 0 1 0 1 0 0 1 1 0 1 1 1 0 As you can see, A0 will alternate for every byte you're accessing. Now, open the datasheet of your display controller and read the description of the RS pin. Putting it to A0 will just fail as you keep switching it, even if you're writing plain image data! Using an address pin for RS a neat little "trick" to map image data as well as control data to your controllers memory space without having to manually switch a GPIO. But it has to be a high address pin (at least, the image data for your whole screen must need less address signals!)

Ouch. As I understand the problem, RS should be tied to a high adress pin. The FSMC of your microcontroller is just an external memory interface. Writing to it (especially with DMA) will increase the memory pointer (which results in changing adress pins). A0 is therefore a bad choice for RS as it will go 0-1-0-1-0-1-0-1 when writing multiple bytes.