Question
FMC accessed in 32-bit, but CS asserted for twice long (64-bits)
Hello,
We access FMC PSRAM in 32-bits.
We noticed that although the access was expected to be in 32-bits (using HAL_SRAM_Read_32b) , CS signal is actually asserted for long of 64-bits!
Is there anything which can explain why the CS is twice the time of the expected access ?
This is the initialization of this interface of bank #3.
As you can see access is also using no wait signal:
{
FMC_NORSRAM_TimingTypeDef Timing;
g_hfpga.Instance = FMC_NORSRAM_DEVICE;
g_hfpga.Extended = FMC_NORSRAM_EXTENDED_DEVICE;
/* g_hfpga.Init , page 821 in reference */
g_hfpga.Init.NSBank = FMC_NORSRAM_BANK2;
g_hfpga.Init.DataAddressMux = FMC_DATA_ADDRESS_MUX_DISABLE;
g_hfpga.Init.MemoryType = FMC_MEMORY_TYPE_PSRAM;
g_hfpga.Init.MemoryDataWidth = FMC_NORSRAM_MEM_BUS_WIDTH_16;
g_hfpga.Init.BurstAccessMode = FMC_BURST_ACCESS_MODE_ENABLE; //This bit enables/disables synchronous accesses during read operations
g_hfpga.Init.WaitSignalPolarity = FMC_WAIT_SIGNAL_POLARITY_LOW;
g_hfpga.Init.WaitSignalActive = FMC_WAIT_TIMING_DURING_WS;
g_hfpga.Init.WriteOperation = FMC_WRITE_OPERATION_ENABLE;
g_hfpga.Init.WaitSignal = FMC_WAIT_SIGNAL_ENABLE;
g_hfpga.Init.ExtendedMode = FMC_EXTENDED_MODE_DISABLE;
g_hfpga.Init.AsynchronousWait = FMC_ASYNCHRONOUS_WAIT_ENABLE;
g_hfpga.Init.WriteBurst = FMC_WRITE_BURST_ENABLE; //<-- this enables synchronous mode
g_hfpga.Init.ContinuousClock = FMC_CONTINUOUS_CLOCK_SYNC_ASYNC; bank1.ContinuousClock
g_hfpga.Init.WriteFifo = FMC_WRITE_FIFO_ENABLE;
g_hfpga.Init.PageSize = FMC_PAGE_SIZE_NONE;
Timing.AddressSetupTime = 7;
Timing.AddressHoldTime = 7;
Timing.DataSetupTime = 50;
Timing.BusTurnAroundDuration = 4;
Timing.CLKDivision = 4; //~200Mhz is clock source
Timing.DataLatency = 4;
Timing.AccessMode = FMC_ACCESS_MODE_A;
...
}Read access timing diagram:
Thank you,
ran