I'm using the FMC of the STM32H743 to drive a 16-bit 8080-bus LCD controller.
I've tried using DMA, MDMA and a CPU-loop to transfer data to the 8080-bus, via the FMC.
The transfer frequency does not depend on whether DMA, MDMA or CPU-loop is used. This make me think that the DMA/MDMA/CPU-loop is not the limiting factor.
At a 480MHz FMC clock, the transfer happens at just 1.6MHz, giving me only 20fps on a 16-bit colour 320x240 LCD.
At a 240MHz FMC clock, the transfer happens at just 0.8MHz, and so on at slower speeds.
I've also tried reducing the various setup and hold times to 1 and 0 cycles, but this has (surprisingly) not affected the waveform on the 8080-bus.
My (Cube-MX generated) FMC initialisation code is:
/* FMC initialization function */
static void MX_FMC_Init(void)
{
/* USER CODE BEGIN FMC_Init 0 */
/* USER CODE END FMC_Init 0 */
FMC_NORSRAM_TimingTypeDef Timing = {0};
FMC_NORSRAM_TimingTypeDef ExtTiming = {0};
/* USER CODE BEGIN FMC_Init 1 */
/* USER CODE END FMC_Init 1 */
/** Perform the SRAM1 memory initialization sequence
*/
hsram1.Instance = FMC_NORSRAM_DEVICE;
hsram1.Extended = FMC_NORSRAM_EXTENDED_DEVICE;
/* hsram1.Init */
hsram1.Init.NSBank = FMC_NORSRAM_BANK2;
hsram1.Init.DataAddressMux = FMC_DATA_ADDRESS_MUX_DISABLE;
hsram1.Init.MemoryType = FMC_MEMORY_TYPE_SRAM;
hsram1.Init.MemoryDataWidth = FMC_NORSRAM_MEM_BUS_WIDTH_16;
hsram1.Init.BurstAccessMode = FMC_BURST_ACCESS_MODE_DISABLE;
hsram1.Init.WaitSignalPolarity = FMC_WAIT_SIGNAL_POLARITY_LOW;
hsram1.Init.WaitSignalActive = FMC_WAIT_TIMING_BEFORE_WS;
hsram1.Init.WriteOperation = FMC_WRITE_OPERATION_ENABLE;
hsram1.Init.WaitSignal = FMC_WAIT_SIGNAL_DISABLE;
hsram1.Init.ExtendedMode = FMC_EXTENDED_MODE_ENABLE;
hsram1.Init.AsynchronousWait = FMC_ASYNCHRONOUS_WAIT_DISABLE;
hsram1.Init.WriteBurst = FMC_WRITE_BURST_DISABLE;
hsram1.Init.ContinuousClock = FMC_CONTINUOUS_CLOCK_SYNC_ONLY;
hsram1.Init.WriteFifo = FMC_WRITE_FIFO_DISABLE;
hsram1.Init.PageSize = FMC_PAGE_SIZE_NONE;
/* Timing */
Timing.AddressSetupTime = 3;
Timing.AddressHoldTime = 15;
Timing.DataSetupTime = 4;
Timing.BusTurnAroundDuration = 1;
Timing.CLKDivision = 16;
Timing.DataLatency = 17;
Timing.AccessMode = FMC_ACCESS_MODE_A;
/* ExtTiming */
ExtTiming.AddressSetupTime = 3;
ExtTiming.AddressHoldTime = 15;
ExtTiming.DataSetupTime = 4;
ExtTiming.BusTurnAroundDuration = 1;
ExtTiming.CLKDivision = 16;
ExtTiming.DataLatency = 17;
ExtTiming.AccessMode = FMC_ACCESS_MODE_A;
if (HAL_SRAM_Init(&hsram1, &Timing, &ExtTiming) != HAL_OK)
{
Error_Handler( );
}
HAL_SetFMCMemorySwappingConfig(FMC_SWAPBMAP_SDRAM_SRAM);
}
My amended settings were:
Timing.AddressSetupTime = 1;
Timing.AddressHoldTime = 1;
Timing.DataSetupTime = 1;
Timing.BusTurnAroundDuration = 1; // not needed
Timing.CLKDivision = 1; // not needed
Timing.DataLatency = 34;
Timing.AccessMode = FMC_ACCESS_MODE_A;
ExtTiming.AddressSetupTime = 1;
ExtTiming.AddressHoldTime = 1;
ExtTiming.DataSetupTime = 1;
ExtTiming.BusTurnAroundDuration = 1; // not needed
ExtTiming.CLKDivision = 1; // not needed
ExtTiming.DataLatency = 34;
ExtTiming.AccessMode = FMC_ACCESS_MODE_A;
and
Timing.AddressSetupTime = 0;
Timing.AddressHoldTime = 0;
Timing.DataSetupTime = 0;
Timing.BusTurnAroundDuration = 0; // not needed
Timing.CLKDivision = 1; // not needed
Timing.DataLatency = 0;
Timing.AccessMode = FMC_ACCESS_MODE_A;
ExtTiming.AddressSetupTime = 0;
ExtTiming.AddressHoldTime = 0;
ExtTiming.DataSetupTime = 0;
ExtTiming.BusTurnAroundDuration = 0; // not needed
ExtTiming.CLKDivision = 1; // not needed
ExtTiming.DataLatency = 34;
ExtTiming.AccessMode = FMC_ACCESS_MODE_A;
The (Cube-MX generated) clock setup is:
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
/** Supply configuration update enable
*/
HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);
/** Configure the main internal regulator output voltage
*/
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE0);
while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
/** Macro to configure the PLL clock source
*/
__HAL_RCC_PLL_PLLSOURCE_CONFIG(RCC_PLLSOURCE_HSE);
/** Initializes the CPU, AHB and APB busses clocks
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 4;
RCC_OscInitStruct.PLL.PLLN = 480;
RCC_OscInitStruct.PLL.PLLP = 2;
RCC_OscInitStruct.PLL.PLLQ = 20;
RCC_OscInitStruct.PLL.PLLR = 2;
RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_1;
RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
RCC_OscInitStruct.PLL.PLLFRACN = 0;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB busses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
|RCC_CLOCKTYPE_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK)
{
Error_Handler();
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_SPI1|RCC_PERIPHCLK_USB
|RCC_PERIPHCLK_QSPI|RCC_PERIPHCLK_FMC;
PeriphClkInitStruct.PLL2.PLL2M = 2;
PeriphClkInitStruct.PLL2.PLL2N = 120;
PeriphClkInitStruct.PLL2.PLL2P = 8;
PeriphClkInitStruct.PLL2.PLL2Q = 2;
PeriphClkInitStruct.PLL2.PLL2R = 1;
PeriphClkInitStruct.PLL2.PLL2RGE = RCC_PLL2VCIRANGE_2;
PeriphClkInitStruct.PLL2.PLL2VCOSEL = RCC_PLL2VCOWIDE;
PeriphClkInitStruct.PLL2.PLL2FRACN = 0;
PeriphClkInitStruct.FmcClockSelection = RCC_FMCCLKSOURCE_PLL2;
PeriphClkInitStruct.QspiClockSelection = RCC_QSPICLKSOURCE_D1HCLK;
PeriphClkInitStruct.Spi123ClockSelection = RCC_SPI123CLKSOURCE_PLL;
PeriphClkInitStruct.UsbClockSelection = RCC_USBCLKSOURCE_PLL;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Enable USB Voltage detector
*/
HAL_PWREx_EnableUSBVoltageDetector();
}
How can I make the FMC on the STM32H743 transfer half-words faster than 1.6MHz, when driven with a 480MHz clock?
To make the FMC run fast, you must configure the bank that you are going to use.
I had mistakenly configured NE2 bank and then used the address which corresponded to the NE1 bank.