玩转STM32F0 Value Line Discovery 之 点亮LED

1、前面介绍了系统时钟配置工具和GPIO配置工具，在这里就可以用到了，笔者看来GPIO工具不利于初学者对STM32的认识，不建议初学者使用，笔者这里也没用用的，只是用的了时钟配置工具。下面简单介绍，系统时钟工具怎么用，其实打开就可以发现，其实excel宏加载文件，很多人不知道如何配置这个宏才能正常使用该工具，即便配置指导就在文件中，笔者初期也是搞了很久才配置好宏，后面发现有个更简单的方法，微软 office 2010.

      1） 打开excel,点击另存为。

      2）选择保存路径，保存类型（关键）选择为：excel 加载宏，点击"保存"。

      3）接着点击原文件中的保存按钮，会弹出 ”另存为“，这里只要更改文件名（避免与原文件冲突），其他不要更改，点击"保存"。

      4）打开第二次保存的文件，就会发现可以配置了。其中，RUN是配置生效，Generate是生成C文件。

2、系统时钟配置为PLL，48M，具体如下；

   

/**
  ******************************************************************************
  * @file    system_stm32f0xx.c
  * @author  MCD Application Team
  * @version V1.0.1
  * @date    14-July-2014
  * @brief   CMSIS Cortex-M0 Device Peripheral Access Layer System Source File.
  *          This file contains the system clock configuration for STM32F0xx devices,
  *          and is generated by the clock configuration tool  
  *          STM32f0xx_Clock_Configuration_V1.0.1.xls
  *
  * 1.  This file provides two functions and one global variable to be called from 
  *     user application:
  *      - SystemInit(): Setups the system clock (System clock source, PLL Multiplier
  *                      and Divider factors, AHB/APBx prescalers and Flash settings),
  *                      depending on the configuration made in the clock xls tool.
  *                      This function is called at startup just after reset and 
  *                      before branch to main program. This call is made inside
  *                      the "startup_stm32f0xx.s" file.
  *
  *      - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
  *                                  by the user application to setup the SysTick 
  *                                  timer or configure other parameters.
  *
  *      - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
  *                                 be called whenever the core clock is changed
  *                                 during program execution.
  *
  * 2. After each device reset the HSI (8 MHz Range) is used as system clock source.
  *    Then SystemInit() function is called, in "startup_stm32f0xx.s" file, to
  *    configure the system clock before to branch to main program.
  *
  * 3. If the system clock source selected by user fails to startup, the SystemInit()
  *    function will do nothing and HSI still used as system clock source. User can 
  *    add some code to deal with this issue inside the SetSysClock() function.
  *
  * 4. The default value of HSE crystal is set to 8MHz, refer to "HSE_VALUE" define
  *    in "stm32f0xx.h" file. When HSE is used as system clock source, directly or
  *    through PLL, and you are using different crystal you have to adapt the HSE
  *    value to your own configuration.
  *
  * 5. This file configures the system clock as follows:
  *=============================================================================
  *=============================================================================
  *        System Clock source                    | PLL(HSI)
  *-----------------------------------------------------------------------------
  *        SYSCLK(Hz)                             | 48000000
  *-----------------------------------------------------------------------------
  *        HCLK(Hz)                               | 48000000
  *-----------------------------------------------------------------------------
  *        AHB Prescaler                          | 1
  *-----------------------------------------------------------------------------
  *        APB Prescaler                          | 1
  *-----------------------------------------------------------------------------
  *        HSE Frequency(Hz)                      | NA
  *----------------------------------------------------------------------------
  *        PLLMUL                                 | 12
  *-----------------------------------------------------------------------------
  *        PREDIV                                 | 2
  *-----------------------------------------------------------------------------
  *        Flash Latency(WS)                      | 1
  *-----------------------------------------------------------------------------
  *        Prefetch Buffer                        | ON
  *-----------------------------------------------------------------------------
  ******************************************************************************
  * @attention
  *
  * 

© COPYRIGHT 2012 STMicroelectronics * * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License"); * You may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.st.com/software_license_agreement_liberty_v2 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * ****************************************************************************** */ /** @addtogroup CMSIS * @{ */ /** @addtogroup stm32f0xx_system * @{ */ /** @addtogroup STM32F0xx_System_Private_Includes * @{ */ #include "stm32f0xx.h" /** * @} */ /** @addtogroup STM32F0xx_System_Private_TypesDefinitions * @{ */ /** * @} */ /** @addtogroup STM32F0xx_System_Private_Defines * @{ */ /** * @} */ /** @addtogroup STM32F0xx_System_Private_Macros * @{ */ /** * @} */ /** @addtogroup STM32F0xx_System_Private_Variables * @{ */ uint32_t SystemCoreClock = 48000000; __I uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9}; /** * @} */ /** @addtogroup STM32F0xx_System_Private_FunctionPrototypes * @{ */ static void SetSysClock(void); /** * @} */ /** @addtogroup STM32F0xx_System_Private_Functions * @{ */ /** * @brief Setup the microcontroller system. * Initialize the Embedded Flash Interface, the PLL and update the * SystemCoreClock variable. * @param None * @retval None */ void SystemInit (void) { /* Set HSION bit */ RCC->CR |= (uint32_t)0x00000001; /* Reset SW[1:0], HPRE[3:0], PPRE[2:0], ADCPRE and MCOSEL[2:0] bits */ RCC->CFGR &= (uint32_t)0xF8FFB80C; /* Reset HSEON, CSSON and PLLON bits */ RCC->CR &= (uint32_t)0xFEF6FFFF; /* Reset HSEBYP bit */ RCC->CR &= (uint32_t)0xFFFBFFFF; /* Reset PLLSRC, PLLXTPRE and PLLMUL[3:0] bits */ RCC->CFGR &= (uint32_t)0xFFC0FFFF; /* Reset PREDIV1[3:0] bits */ RCC->CFGR2 &= (uint32_t)0xFFFFFFF0; /* Reset USARTSW[1:0], I2CSW, CECSW and ADCSW bits */ RCC->CFGR3 &= (uint32_t)0xFFFFFEAC; /* Reset HSI14 bit */ RCC->CR2 &= (uint32_t)0xFFFFFFFE; /* Disable all interrupts */ RCC->CIR = 0x00000000; /* Configure the System clock frequency, AHB/APBx prescalers and Flash settings */ SetSysClock(); } /** * @brief Update SystemCoreClock according to Clock Register Values * The SystemCoreClock variable contains the core clock (HCLK), it can * be used by the user application to setup the SysTick timer or configure * other parameters. * * @note Each time the core clock (HCLK) changes, this function must be called * to update SystemCoreClock variable value. Otherwise, any configuration * based on this variable will be incorrect. * * @note - The system frequency computed by this function is not the real * frequency in the chip. It is calculated based on the predefined * constant and the selected clock source: * * - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(*) * * - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(**) * * - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(**) * or HSI_VALUE(*) multiplied/divided by the PLL factors. * * (*) HSI_VALUE is a constant defined in stm32f0xx.h file (default value * 8 MHz) but the real value may vary depending on the variations * in voltage and temperature. * * (**) HSE_VALUE is a constant defined in stm32f0xx.h file (default value * 8 MHz), user has to ensure that HSE_VALUE is same as the real * frequency of the crystal used. Otherwise, this function may * have wrong result. * * - The result of this function could be not correct when using fractional * value for HSE crystal. * @param None * @retval None */ void SystemCoreClockUpdate (void) { uint32_t tmp = 0, pllmull = 0, pllsource = 0, prediv1factor = 0; /* Get SYSCLK source -------------------------------------------------------*/ tmp = RCC->CFGR & RCC_CFGR_SWS; switch (tmp) { case 0x00: /* HSI used as system clock */ SystemCoreClock = HSI_VALUE; break; case 0x04: /* HSE used as system clock */ SystemCoreClock = HSE_VALUE; break; case 0x08: /* PLL used as system clock */ /* Get PLL clock source and multiplication factor ----------------------*/ pllmull = RCC->CFGR & RCC_CFGR_PLLMULL; pllsource = RCC->CFGR & RCC_CFGR_PLLSRC; pllmull = ( pllmull >> 18) + 2; if (pllsource == 0x00) { /* HSI oscillator clock divided by 2 selected as PLL clock entry */ SystemCoreClock = (HSI_VALUE >> 1) * pllmull; } else { prediv1factor = (RCC->CFGR2 & RCC_CFGR2_PREDIV1) + 1; /* HSE oscillator clock selected as PREDIV1 clock entry */ SystemCoreClock = (HSE_VALUE / prediv1factor) * pllmull; } break; default: /* HSI used as system clock */ SystemCoreClock = HSI_VALUE; break; } /* Compute HCLK clock frequency ----------------*/ /* Get HCLK prescaler */ tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)]; /* HCLK clock frequency */ SystemCoreClock >>= tmp; } /** * @brief Configures the System clock frequency, AHB/APBx prescalers and Flash * settings. * @note This function should be called only once the RCC clock configuration * is reset to the default reset state (done in SystemInit() function). * @param None * @retval None */ static void SetSysClock(void) { /******************************************************************************/ /* PLL (clocked by HSI) used as System clock source */ /******************************************************************************/ /* At this stage the HSI is already enabled and used as System clock source */ /* SYSCLK, HCLK, PCLK configuration ----------------------------------------*/ /* Enable Prefetch Buffer and set Flash Latency */ FLASH->ACR = FLASH_ACR_PRFTBE | FLASH_ACR_LATENCY; /* HCLK = SYSCLK / 1 */ RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1; /* PCLK = HCLK / 1 */ RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE_DIV1; /* PLL configuration */ RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMULL)); RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_HSI_Div2 | RCC_CFGR_PLLXTPRE_PREDIV1 | RCC_CFGR_PLLMULL12); /* Enable PLL */ RCC->CR |= RCC_CR_PLLON; /* Wait till PLL is ready */ while((RCC->CR & RCC_CR_PLLRDY) == 0) { } /* Select PLL as system clock source */ RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW)); RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL; /* Wait till PLL is used as system clock source */ while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)RCC_CFGR_SWS_PLL) { } } /** * @} */ /** * @} */ /** * @} */ /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

3、配置GPIO --- LED3：PC9; LED4：PC8 ,根据原理图可知；IO应配置成输出，如题代码如下

   

   

#include "Gpio.h"


/*
 * LED3:PC9 ;  LED4:PC8
 *
*/
void LED_init(void)
{
	GPIO_InitTypeDef GPIO_InitStructure;

	RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC, ENABLE);

	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9;
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

	GPIO_Init(GPIOC, &GPIO_InitStructure);
	
}

4.GPIO配置好了，就只需在MAIN函数中调用一下，然后，在循环中，适当延长一段时间，并改变一下对外输出的电平LED就可以闪烁了，具体代码如下，这里笔者用的的是systick定时器进行延时，下次再对这个定时器做详细介绍。
  

  

/**
  ******************************************************************************
  * @file    main.c 
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    02-October-2013
  * @brief   Main program body
  ******************************************************************************
  * @attention
  *
  * 

© COPYRIGHT 2013 STMicroelectronics * * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License"); * You may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.st.com/software_license_agreement_liberty_v2 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * ****************************************************************************** */ /* Includes ------------------------------------------------------------------*/ #include "main.h" #include "Gpio.h" /** @addtogroup STM32F0308-Discovery_Demo * @{ */ /* Private typedef -----------------------------------------------------------*/ /* Private define ------------------------------------------------------------*/ /* Private macro -------------------------------------------------------------*/ /* Private variables ---------------------------------------------------------*/ static __IO uint32_t TimingDelay; uint8_t BlinkSpeed = 0; /* Private function prototypes -----------------------------------------------*/ /* Private functions ---------------------------------------------------------*/ /** * @brief Main program. * @param None * @retval None */ int main(void) { RCC_ClocksTypeDef RCC_Clocks; LED_init(); /* SysTick end of count event each 1ms */ RCC_GetClocksFreq(&RCC_Clocks); SysTick_Config(RCC_Clocks.HCLK_Frequency / 1000); /* Initiate Blink Speed variable */ BlinkSpeed = 1; while(1){ if(GPIO_ReadOutputDataBit(GPIOC, GPIO_Pin_8) == Bit_SET) { GPIO_WriteBit(GPIOC, GPIO_Pin_8, Bit_RESET); } else{ GPIO_WriteBit(GPIOC, GPIO_Pin_8, Bit_SET); } if(GPIO_ReadOutputDataBit(GPIOC, GPIO_Pin_9) == Bit_SET) { GPIO_WriteBit(GPIOC, GPIO_Pin_9, Bit_RESET); } else{ GPIO_WriteBit(GPIOC, GPIO_Pin_9, Bit_SET); } Delay(300); } } /** * @brief Inserts a delay time. * @param nTime: specifies the delay time length, in 1 ms. * @retval None */ void Delay(__IO uint32_t nTime) { TimingDelay = nTime; while(TimingDelay != 0); } /** * @brief Decrements the TimingDelay variable. * @param None * @retval None */ void TimingDelay_Decrement(void) { if (TimingDelay != 0x00) { TimingDelay--; } } #ifdef USE_FULL_ASSERT /** * @brief Reports the name of the source file and the source line number * where the assert_param error has occurred. * @param file: pointer to the source file name * @param line: assert_param error line source number * @retval None */ void assert_failed(uint8_t* file, uint32_t line) { /* User can add his own implementation to report the file name and line number, ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */ /* Infinite loop */ while (1) {} } #endif /** * @} */ /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

5、至此，LED可以闪烁了，对GPIO可以用初步认识了。