I have developed a board on which a STM32F205 microcontroller is connected to an asynchronous external SRAM (ISSI IS61WV102416BLL) which has read/write access times of 10ns. This RAM is used as a picture buffer.
I configured the FSMC bus as follows:
- Normal mode (mode 1)
- ADDSET = 2 HCLK cycles
- DATAST = 2 HCLK cycles
where HCLK is 120MHz.
I measured the NE and NWE lines for one write access and saw that ADDSET lasts 1.62us and the memory transaction, 8.52us. Considering the memory read/write access time of 10ns and the FSMC configuration, I expected something more like 16ns for ADDSET and 32ns for the memory transaction which is more that 200x faster that what I have today.
Am I missing something or where should I focus on to improve this poor memory performance?
Thank you in advance for your help.