the boot time of 60ms is too long for STM32L031K6 with the Nucleo EVK

[Rob Wei]

Posted on November 28, 2017 at 04:08

Dear there,

 I'm using the Nucleo STM32L031K6 EVK as a 12MHZ SPI slave in my application. Now I found it takes about 60ms from VDD ready to finishing excetution of below code snippet so the SPI slave misses some cmd of SPI master. How can I reduce the boot time to below 20ms(lesser is better)? Thank you very much.

   HAL_Init();

  /* Configure the system clock to 32 MHz */

  SystemClock32m_Config();  MX_GPIO_Init();

//============================

void SystemClock32m_Config(void)

{  RCC_OscInitTypeDef RCC_OscInitStruct;  RCC_ClkInitTypeDef RCC_ClkInitStruct;  RCC_PeriphCLKInitTypeDef PeriphClkInit;    /**Configure the main internal regulator output voltage     */  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);    /**Initializes the CPU, AHB and APB busses clocks     */  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;  RCC_OscInitStruct.HSIState = RCC_HSI_ON;  RCC_OscInitStruct.HSICalibrationValue = 16;  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLLMUL_4;  RCC_OscInitStruct.PLL.PLLDIV = RCC_PLLDIV_2;  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)  {    Error_Handler(__FILE__, __LINE__);  }    /**Initializes the CPU, AHB and APB busses clocks     */  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)  {    Error_Handler(__FILE__, __LINE__);  }  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_I2C1;  PeriphClkInit.I2c1ClockSelection = RCC_I2C1CLKSOURCE_PCLK1;  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)  {    Error_Handler(__FILE__, __LINE__);  }    /**Configure the Systick interrupt time     */  HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);    /**Configure the Systick     */  HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);  /* SysTick_IRQn interrupt configuration */  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);}#stm32 #spi #boot-time

[Rob Wei]

Posted on November 29, 2017 at 11:07

Hi There,

 I have new finding today. Actually, on the entry of the main() it already takes about 60ms.

 So what happen before that? I went through the Reset_Handler and found it just call SystemInit before branching into main( ). And the SystemInit looks simple. So how does the 60mS come from? Any idea is appreciated.

[Marcus Peter]

Posted on February 09, 2018 at 11:39

Hi There,

I have the same problem with stm32L452. From reset to main it takes more than 4ms which is too long for my apllication. Have you found a solution for the long boot time ?

[Tesla DeLorean]

Posted on February 09, 2018 at 17:44

Probably by running off the MSI clock it started with rather than enable and wait for other clocks and PLLs to start?

[henry.dick]

Posted on February 09, 2018 at 20:00

'

How can I reduce the boot time to below 20ms(lesser is better)?

 '

not sure how you measured it but it is entirely possible that the actual time is considerably shorter / longer than what you thought it was.

with that said, a few things will help you speed up the process:

1) use an external oscillator - hopefully with a quick start-up time.

2) disable PLL.

3) roll your own configuration code so you don't incur the library related bloat. 60ms for a 32-bit chip is like enternity.

4) the most effective: start your chip first before anything else.

...

[T J]

Posted on February 10, 2018 at 02:02

If you have a low impedance power supply,

the 3V rise time would be sharper,

then your reset would be quicker.

but you may only gain 10-20mS.