STM32L4 slow toggling GPIO pins

Question

So for my project I use STM32L4R5 (custom PCB) and need to connect parallel 8 wires to control addresses in a sensor. I am toggling 8 GPIO pins in parallel providing the addresses, but speed is crazy low (I would need 10~20MHz). I checked several other similar problems in different sites and optimized as much as I can. I guess it may be very simple error but what I have at the moment is as follows:

MXCube settings:

basically, I have 48MHz crystal, I use PLL to go up to 100MHz for system clock, 80MHz for ADC (different topic...). I actually touched the code a few times testing between 48MHz and less so I paste also the final clock settings in code:

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

  if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI48|RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.HSI48State = RCC_HSI48_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLM = 12;
  RCC_OscInitStruct.PLL.PLLN = 50;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
  RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;//RCC_SYSCLKSOURCE_HSE;//RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;//RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;//RCC_HCLK_DIV4;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK)
  {
    Error_Handler();
  }


  if(vers==1){
      PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_I2C1|RCC_PERIPHCLK_USB
                                  |RCC_PERIPHCLK_ADC;
      PeriphClkInit.I2c1ClockSelection = RCC_I2C1CLKSOURCE_PCLK1;
      PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_PLLSAI1;//RCC_ADCCLKSOURCE_SYSCLK
      PeriphClkInit.UsbClockSelection = RCC_USBCLKSOURCE_HSI48;
      PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_HSE;
      PeriphClkInit.PLLSAI1.PLLSAI1M = 6;
      PeriphClkInit.PLLSAI1.PLLSAI1N = 20;
      PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV2;
      PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV2;
      PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV2;
      PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_ADC1CLK;
  }
  if(vers==2){
      PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_I2C1|RCC_PERIPHCLK_ADC;
      PeriphClkInit.I2c1ClockSelection = RCC_I2C1CLKSOURCE_SYSCLK;//RCC_I2C1CLKSOURCE_PCLK1;
      PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_PLLSAI1;//RCC_ADCCLKSOURCE_PLLSAI1;//RCC_ADCCLKSOURCE_SYSCLK
      PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_HSE;
      PeriphClkInit.PLLSAI1.PLLSAI1M = 6;
      PeriphClkInit.PLLSAI1.PLLSAI1N = 20;
      PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV2;
      PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV2;
      PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV2;
      PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_ADC1CLK;
  }


  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }

  //__HAL_FLASH_SET_LATENCY(FLASH_LATENCY_4);
  __HAL_FLASH_PREFETCH_BUFFER_ENABLE();
  __HAL_FLASH_DATA_CACHE_ENABLE();

}

I added 4 Flash wait states according to the reference manual. Now we reach the funny part. My original code was change into the BSRR register (commented in the loop). I noticed this line takes about 30 tics to execute. So I made an array "lineindex" with all 32bit values to be written in BSRR, no calculations required; Oscilloscope on the lowest pin gave me this:

I was surprised by the low value. Run from flash/RAM brought like 100-200kHz difference. So spent 2 days studying how to do the same using DMA. Now I use TIM1 to trigger DMA to make MEM2PERIPH transfer (MEM source is the 32bit word array, sending data through DMA directly to BSRR). If I get it right MCU is not used during the burst sends (160transfers at once), manual says bus can run on 120MHz (set at 100MHz now), so... what happens? Code:

//Timer
static void MX_TIM1_Init(void)
{


    /* 3 (Timer TIM1) */
    __HAL_RCC_TIM1_CLK_ENABLE();
    htim1.Instance = TIM1;
    htim1.Init.Prescaler = 0;
    htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
    htim1.Init.Period = 7;
    htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
    htim1.Init.RepetitionCounter = 0;
    HAL_TIM_Base_Init(&htim1);
      /* 7 (Enable TIM for DMA events) */
    __HAL_TIM_ENABLE_DMA(&htim1, TIM_DMA_UPDATE);

  TIM_ClockConfigTypeDef sClockSourceConfig = {0};

  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim1, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }

}


// DMA2 (includes ADC code on channel3, channel6 is used for the current loop)
static void MX_DMA_Init(void)
{

  /* DMA controller clock enable */
  __HAL_RCC_DMAMUX1_CLK_ENABLE();
  __HAL_RCC_DMA2_CLK_ENABLE();
  __DMA2_CLK_ENABLE();

  /* DMA interrupt init */
  hdma_adc1.Instance = DMA2_Channel3;
  hdma_adc1.Init.Direction = DMA_PERIPH_TO_MEMORY;
  hdma_adc1.Init.PeriphInc = DMA_PINC_DISABLE;
  hdma_adc1.Init.MemInc = DMA_MINC_ENABLE;
  hdma_adc1.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;
  hdma_adc1.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
  hdma_adc1.Init.Mode = DMA_CIRCULAR;
  hdma_adc1.Init.Priority = DMA_PRIORITY_HIGH;
  //HAL_DMA_DeInit(&hdma_adc1);
  HAL_DMA_Init(&hdma_adc1);
  __HAL_LINKDMA(&hadc1, DMA_Handle, hdma_adc1);

  DMAMUX1_Channel9->CCR &= ~( DMAMUX_CxCR_DMAREQ_ID );
  DMAMUX1_Channel9->CCR = 0x5;


    /* 4 (DMA2 Channel6) */
    hdma_tim1_uev.Instance = DMA2_Channel6;
    hdma_tim1_uev.Init.Direction = DMA_MEMORY_TO_PERIPH;
    hdma_tim1_uev.Init.PeriphInc = DMA_PINC_DISABLE;
    hdma_tim1_uev.Init.MemInc = DMA_MINC_ENABLE;
    hdma_tim1_uev.Init.PeriphDataAlignment = DMA_PDATAALIGN_WORD; // 16 bits
    hdma_tim1_uev.Init.MemDataAlignment = DMA_MDATAALIGN_WORD;
    hdma_tim1_uev.Init.Mode = DMA_NORMAL;
    hdma_tim1_uev.Init.Priority = DMA_PRIORITY_LOW;
    HAL_DMA_Init(&hdma_tim1_uev);
    __HAL_LINKDMA(&htim1,hdma[TIM_DMA_ID_UPDATE],hdma_tim1_uev);

    DMAMUX1_Channel12->CCR &= ~( DMAMUX_CxCR_DMAREQ_ID );
    DMAMUX1_Channel12->CCR = 46U;

  //DMAMUX1_Channel9->CCR &= ~( DMAMUX_CxCR_DMAREQ_ID );
  //DMAMUX1_Channel9->CCR |=  ( 0x8 << DMAMUX_CxCR_DMAREQ_ID_Pos );




  /* DMA interrupt init */
  /* DMA1_Channel1_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA2_Channel3_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA2_Channel3_IRQn);

  HAL_NVIC_SetPriority(DMA2_Channel6_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA2_Channel6_IRQn);

  /* DMAMUX1_OVR_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMAMUX1_OVR_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMAMUX1_OVR_IRQn);

}



// Loop in main
for (counteri=1;counteri<100000;counteri++){
      HAL_DMA_Start_IT(htim1.hdma[TIM_DMA_ID_UPDATE],(uint32_t) lineindex,(uint32_t)&GPIOF->BSRR, 160);

      __HAL_TIM_ENABLE(&htim1);

      while((TIM1->CR1 & 1U));

}

What I get as speed is:

I know the timer Period is a magic number. Changed timer speed from like 5MHz to 50MHz. The shown magic number leads to the maximum loop speed of 6MHz I got, so just left it there.

Now the questions. What am I doing wrong? In other posts I saw reasonable speeds of 15-20MHz with pin toggle function. Direct writing in the registers and even excluding the MCU did not help. I guess it is either some clock error I don't see, or just bus waiting, but it looks strange since there is nothing else going there at the moment. I noticed that in debug mode one asm("NOP"); takes 4 tics. No change regardless whether I run from Flash or RAM (thought it is wait states at first). On slower clock I couldn't even reach 1MHz. Also, big worry is the transient peaks. -0.7~-0.8V to 4V? I wonder whether this is some oscilloscope settings issue or it is normal?

To add more, the code bellow is used since I read analog data from the sensor:

for (counteri=1;counteri<100000;counteri++){

    for(uint8_t vc = 1; vc < 321; vc++){

        GPIOF -> BSRR = lineindex[vc-1];//(vc) | (((~vc) & 0xFF) << (16)); //col

                    asm("NOP");

                    ADC1->CR =268435461U;//|= 4U;                                                    // start ADC reading
                while(!(ADC1->ISR & ADC_ISR_EOS));                                 // wait for ADC conversion to complete
            ADC1->ISR &= 14U;
    }

}

More magic numbers, but tried to eliminate all possible calculations even when values are written in registers. So, with ADC, reading 4 channels using DMA, at 80MHz, 2.5cycles sampling, 12bit, I got less than 500kHz. ADC should be 5.88Msps, 4 channels with some overhead, I would expect at least double, but please if you have any ideas correct me:

Answer 1

50 MHz is the maximum of the GPIO via a timer output.
10 MHz is the maximum when running bare assembler from ram (10 instructions).

What speed can you get in circular DMA with two transactions no triggers?
I guess about 25 Mhz, maybe slower. (4 bus ops)