Posted on August 14, 2015 at 01:31Hi all
I use the STM32429I-EVAL1 board and I did some memory performance measurements (no DMA). The results were a bit strange, as writing to memory is about 50% faster than reading:
@180MHz
write mbs/read mbs
byte 28.57/14.67
word 136.89/53.05
I suspect the memory init code has some errors - for example it doesn't matter what option I use for the burst mode. My init Code looks like this:
sdramHandle.Init.SDBank = FMC_SDRAM_BANK1;
sdramHandle.Init.InternalBankNumber = FMC_SDRAM_INTERN_BANKS_NUM_4;
sdramHandle.Init.CASLatency = FMC_SDRAM_CAS_LATENCY_2;
sdramHandle.Init.WriteProtection = FMC_SDRAM_WRITE_PROTECTION_DISABLE;
sdramHandle.Init.SDClockPeriod = FMC_SDRAM_CLOCK_PERIOD_2;
sdramHandle.Init.ReadBurst = FMC_SDRAM_RBURST_ENABLE;
sdramHandle.Init.ReadPipeDelay = FMC_SDRAM_RPIPE_DELAY_0;
sdramHandle.Init.ColumnBitsNumber = FMC_SDRAM_COLUMN_BITS_NUM_9;
sdramHandle.Init.RowBitsNumber = FMC_SDRAM_ROW_BITS_NUM_12;
sdramHandle.Init.MemoryDataWidth = FMC_SDRAM_MEM_BUS_WIDTH_32;
void BSP_SDRAM_Initialization_sequence(uint32_t RefreshCount)
{
__IO uint32_t tmpmrd = 0;
/* Step 1: Configure a clock configuration enable command */
Command.CommandMode = FMC_SDRAM_CMD_CLK_ENABLE;
Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
Command.AutoRefreshNumber = 1;
Command.ModeRegisterDefinition = 0;
/* Send the command */
HAL_SDRAM_SendCommand(&sdramHandle, &Command, SDRAM_TIMEOUT);
/* Step 2: Insert 100 us minimum delay */
/* Inserted delay is equal to 1 ms due to systick time base unit (ms) */
cyg_thread_delay(1);
/* Step 3: Configure a PALL (precharge all) command */
Command.CommandMode = FMC_SDRAM_CMD_PALL;
Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
Command.AutoRefreshNumber = 1;
Command.ModeRegisterDefinition = 0;
/* Send the command */
HAL_SDRAM_SendCommand(&sdramHandle, &Command, SDRAM_TIMEOUT);
/* Step 4: Configure an Auto Refresh command */
Command.CommandMode = FMC_SDRAM_CMD_AUTOREFRESH_MODE;
Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
Command.AutoRefreshNumber = 8;
Command.ModeRegisterDefinition = 0;
/* Send the command */
HAL_SDRAM_SendCommand(&sdramHandle, &Command, SDRAM_TIMEOUT);
/* Step 5: Program the external memory mode register */
tmpmrd = (uint32_t)SDRAM_MODEREG_BURST_LENGTH_4 |\
SDRAM_MODEREG_BURST_TYPE_SEQUENTIAL |\
SDRAM_MODEREG_CAS_LATENCY_2 |\
SDRAM_MODEREG_OPERATING_MODE_STANDARD |\
SDRAM_MODEREG_WRITEBURST_MODE_SINGLE;
Command.CommandMode = FMC_SDRAM_CMD_LOAD_MODE;
Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
Command.AutoRefreshNumber = 1;
Command.ModeRegisterDefinition = tmpmrd;
/* Send the command */
HAL_SDRAM_SendCommand(&sdramHandle, &Command, SDRAM_TIMEOUT);
/* Step 6: Set the refresh rate counter */
/* Set the device refresh rate */
HAL_SDRAM_ProgramRefreshRate(&sdramHandle, RefreshCount);
}
Do you have a clue what could be wrong?
BR
Michael
#dram-throughput
