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External SRAM (FSMC) poor performance

Question asked by johsey on Mar 26, 2013
Latest reply on Mar 27, 2013 by fm
Dear all,

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.