mbed-os/targets/TARGET_STM/TARGET_STM32L1/TARGET_STM32L152xE/system_clock.c

/* mbed Microcontroller Library
 * SPDX-License-Identifier: BSD-3-Clause
 ******************************************************************************
 *
 * Copyright (c) 2016-2020 STMicroelectronics.
 * All rights reserved.
 *
 * This software component is licensed by ST under BSD 3-Clause license,
 * the "License"; You may not use this file except in compliance with the
 * License. You may obtain a copy of the License at:
 *                        opensource.org/licenses/BSD-3-Clause
 *
 ******************************************************************************
 */

/**
  * This file configures the system clock as follows:
  *-----------------------------------------------------------------
  * System clock source | 1- USE_PLL_HSE_EXTC (external 8 MHz clock)
  *                     | 2- USE_PLL_HSE_XTAL (external 8 MHz xtal)
  *                     | 3- USE_PLL_HSI (internal 16 MHz)
  *-----------------------------------------------------------------
  * SYSCLK(MHz)         | 32
  * AHBCLK (MHz)        | 32
  * APB1CLK (MHz)       | 32
  * USB capable         | YES
  *-----------------------------------------------------------------
  */

#include "stm32l1xx.h"
#include "mbed_error.h"

#define USE_PLL_HSE_EXTC     0x8  // Use external clock (ST Link MCO)
#define USE_PLL_HSE_XTAL     0x4  // Use external xtal (X3 on board - not provided by default)
#define USE_PLL_HSI          0x2  // Use HSI internal clock

#if ( ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) )
uint8_t SetSysClock_PLL_HSE(uint8_t bypass);
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) */

#if ((CLOCK_SOURCE) & USE_PLL_HSI)
uint8_t SetSysClock_PLL_HSI(void);
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSI) */


MBED_WEAK void SetSysClock(void)
{
#if ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC)
    /* 1- Try to start with HSE and external clock */
    if (SetSysClock_PLL_HSE(1) == 0)
#endif
    {
#if ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL)
        /* 2- If fail try to start with HSE and external xtal */
        if (SetSysClock_PLL_HSE(0) == 0)
#endif
        {
#if ((CLOCK_SOURCE) & USE_PLL_HSI)
            /* 3- If fail start with HSI clock */
            if (SetSysClock_PLL_HSI() == 0)
#endif
            {
                {
                    error("SetSysClock failed\n");
                }
            }
        }
    }

    /* Output clock on MCO1 pin(PA8) for debugging purpose */
    //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_SYSCLK, RCC_MCODIV_1);
}

#if ( ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) )
/******************************************************************************/
/*            PLL (clocked by HSE) used as System clock source                */
/******************************************************************************/
MBED_WEAK uint8_t SetSysClock_PLL_HSE(uint8_t bypass)
{
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
    RCC_OscInitTypeDef RCC_OscInitStruct;

    /* Used to gain time after DeepSleep in case HSI is used */
    if (__HAL_RCC_GET_FLAG(RCC_FLAG_HSIRDY) != RESET) {
        return 0;
    }

    /* The voltage scaling allows optimizing the power consumption when the device is
       clocked below the maximum system frequency, to update the voltage scaling value
       regarding system frequency refer to product datasheet. */
    __PWR_CLK_ENABLE();
    __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

    /* Enable HSE oscillator and activate PLL with HSE as source */
    RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSE;
    if (bypass == 0) {
        RCC_OscInitStruct.HSEState          = RCC_HSE_ON; /* External 8 MHz xtal on OSC_IN/OSC_OUT */
    } else {
        RCC_OscInitStruct.HSEState          = RCC_HSE_BYPASS; /* External 8 MHz clock on OSC_IN */
    }
    RCC_OscInitStruct.HSIState            = RCC_HSI_OFF;
    // SYSCLK = 32 MHz (8 MHz *12 /3)
    // USBCLK = 48 MHz (8 MHz *12 /2)
    RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSE;
    RCC_OscInitStruct.PLL.PLLMUL          = RCC_PLL_MUL12;
    RCC_OscInitStruct.PLL.PLLDIV          = RCC_PLL_DIV3;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        return 0; // FAIL
    }

    /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
    RCC_ClkInitStruct.ClockType      = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
    RCC_ClkInitStruct.SYSCLKSource   = RCC_SYSCLKSOURCE_PLLCLK; // 32 MHz
    RCC_ClkInitStruct.AHBCLKDivider  = RCC_SYSCLK_DIV1;         // 32 MHz
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK) {
        return 0; // FAIL
    }

    /* Output clock on MCO1 pin(PA8) for debugging purpose */
    //if (bypass == 0)
    //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSE, RCC_MCODIV_2); // 4 MHz
    //else
    //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSE, RCC_MCODIV_1); // 8 MHz

    return 1; // OK
}
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) */

#if ((CLOCK_SOURCE) & USE_PLL_HSI)
/******************************************************************************/
/*            PLL (clocked by HSI) used as System clock source                */
/******************************************************************************/
uint8_t SetSysClock_PLL_HSI(void)
{
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
    RCC_OscInitTypeDef RCC_OscInitStruct;

    /* The voltage scaling allows optimizing the power consumption when the device is
       clocked below the maximum system frequency, to update the voltage scaling value
       regarding system frequency refer to product datasheet. */
    __PWR_CLK_ENABLE();
    __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

    /* Enable HSI oscillator and activate PLL with HSI as source */
    RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSI;
    RCC_OscInitStruct.HSEState            = RCC_HSE_OFF;
    RCC_OscInitStruct.HSIState            = RCC_HSI_ON;
    RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
    // SYSCLK = 32 MHz (16 MHz *6 /3)
    // USBCLK = 48 MHz (16 MHz *6 /2)
    RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSI;
    RCC_OscInitStruct.PLL.PLLMUL          = RCC_PLL_MUL6;
    RCC_OscInitStruct.PLL.PLLDIV          = RCC_PLL_DIV3;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        return 0; // FAIL
    }

    /* Poll VOSF bit of in PWR_CSR. Wait until it is reset to 0 */
    while (__HAL_PWR_GET_FLAG(PWR_FLAG_VOS) != RESET) {};

    /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
    RCC_ClkInitStruct.ClockType      = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
    RCC_ClkInitStruct.SYSCLKSource   = RCC_SYSCLKSOURCE_PLLCLK; // 32 MHz
    RCC_ClkInitStruct.AHBCLKDivider  = RCC_SYSCLK_DIV1;         // 32 MHz
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK) {
        return 0; // FAIL
    }

    /* Output clock on MCO1 pin(PA8) for debugging purpose */
    //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSI, RCC_MCODIV_1); // 16 MHz

    return 1; // OK
}
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSI) */