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SRAM FMC not working


Hello all,

I'm trying to communicate with SRAM device on my board.

I'm using STM32H747XIH6 MCU.

I tried to capture the Write enable, chip select and output enable pins on the board but I saw an unusual response of the output enable.

My configuration for the SRAM is as follows

/** Perform the SRAM2 memory initialization sequence
  hsram2.Instance = FMC_NORSRAM_DEVICE;
  /* hsram2.Init */
  hsram2.Init.NSBank = FMC_NORSRAM_BANK2;
  hsram2.Init.DataAddressMux = FMC_DATA_ADDRESS_MUX_DISABLE;
  hsram2.Init.MemoryType = FMC_MEMORY_TYPE_SRAM;
  hsram2.Init.MemoryDataWidth = FMC_NORSRAM_MEM_BUS_WIDTH_32;
  hsram2.Init.BurstAccessMode = FMC_BURST_ACCESS_MODE_DISABLE;
  hsram2.Init.WaitSignalPolarity = FMC_WAIT_SIGNAL_POLARITY_LOW;
  hsram2.Init.WaitSignalActive = FMC_WAIT_TIMING_BEFORE_WS;
  hsram2.Init.WriteOperation = FMC_WRITE_OPERATION_ENABLE;
  hsram2.Init.WaitSignal = FMC_WAIT_SIGNAL_DISABLE;
  hsram2.Init.ExtendedMode = FMC_EXTENDED_MODE_DISABLE;
  hsram2.Init.AsynchronousWait = FMC_ASYNCHRONOUS_WAIT_DISABLE;
  hsram2.Init.WriteBurst = FMC_WRITE_BURST_DISABLE;
  hsram2.Init.ContinuousClock = FMC_CONTINUOUS_CLOCK_SYNC_ONLY;
  hsram2.Init.WriteFifo = FMC_WRITE_FIFO_DISABLE;
  hsram2.Init.PageSize = FMC_PAGE_SIZE_NONE;
  /* Timing */
  Timing.AddressSetupTime = 6;
  Timing.AddressHoldTime = 15;
  Timing.DataSetupTime = 12;
  Timing.BusTurnAroundDuration = 3;
  Timing.CLKDivision = 16;
  Timing.DataLatency = 17;
  Timing.AccessMode = FMC_ACCESS_MODE_A;
  /* ExtTiming */
  if (HAL_SRAM_Init(&hsram2, &Timing, NULL) != HAL_OK)
    Error_Handler( );

The captured waveform is attached below0693W00000aH8aoQAC.pngBlue : Write Enable

Yellow : Chip Select

Pink : Output enable.

I do not understand why does the output enable toggle multiple times for one write/read operation.


Cortex-M7 are complex. Do some background reading.

How is this area defined in MPU?

Reads to Cacheable areas result in cache line fill, read to non-cacheable but Normal areas are subject to speculative prefetch.