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STM32F072B-DISCO 深入研究
STM32F072B-DISCO 是我认为性价比最高的一款CPU的demo系统，以前一直在用PIC的CPU但最近几年ST异军突起，几次课题查找芯片无一例外都是ST，像USB,CAN,ZIGBEE等，ST都做的很出色，特别是芯片太便宜了，几乎都是几块人民币，STM32F072B-DISCO 提供了大量例题，我通过对例题的分析做出简单扼要的笔记，以加深自己的理解。
第一篇：中断系统
我认为理解和掌握中断系统是会使CPU的唯一标准。
int main(void)
{
/*!< At this stage the microcontroller clock setting is already configured,
this is done through SystemInit() function which is called from startup
file (startup_stm32f0xx.s) before to branch to application main.
To reconfigure the default setting of SystemInit() function, refer to
system_stm32f0xx.c file
*/
所有例题开始都有这么一段注释，在进入main之前CPU已经完成了一系列初始化工作，startup_stm32f0xx.s在后面必须认真分析
/* Initialize LEDs mounted on STM32F072B-DISCO board */
STM_EVAL_LEDInit(LED3);
STM_EVAL_LEDInit(LED4);
STM_EVAL_LEDInit(LED5);
STM_EVAL_LEDInit(LED6);
/* Configure PA0 in interrupt mode */
EXTI0_1_Config(); // 外部中断 0 1 配置
配置中断子程序
static void EXTI0_1_Config(void)
{
/* Enable GPIOA clock */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
/* Configure PA0 pin as input floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Enable SYSCFG clock */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
/* Connect EXTI0 Line to PA0 pin */
SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);
/* Configure EXTI0 line */
EXTI_InitStructure.EXTI_Line = EXTI_Line0;
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);
/* Enable and set EXTI0 Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 0x00;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure); 开中断并设定优先级
}
打开stm32f0xx_misc.c
void NVIC_Init(NVIC_InitTypeDef* NVIC_InitStruct)
{
uint32_t tmppriority = 0x00;
/* Check the parameters */
assert_param(IS_FUNCTIONAL_STATE(NVIC_InitStruct->NVIC_IRQChannelCmd));
assert_param(IS_NVIC_PRIORITY(NVIC_InitStruct->NVIC_IRQChannelPriority));
if (NVIC_InitStruct->NVIC_IRQChannelCmd != DISABLE)
{
/* Compute the Corresponding IRQ Priority --------------------------------*/
tmppriority = NVIC->IP[NVIC_InitStruct->NVIC_IRQChannel >> 0x02];
tmppriority &= (uint32_t)(~(((uint32_t)0xFF) << ((NVIC_InitStruct->NVIC_IRQChannel & 0x03) * 8)));
tmppriority |= (uint32_t)((((uint32_t)NVIC_InitStruct->NVIC_IRQChannelPriority << 6) & 0xFF) << ((NVIC_InitStruct->NVIC_IRQChannel & 0x03) * 8));
NVIC->IP[NVIC_InitStruct->NVIC_IRQChannel >> 0x02] = tmppriority; 设定优先级
/* Enable the Selected IRQ Channels --------------------------------------*/
NVIC->ISER[0] = (uint32_t)0x01 << (NVIC_InitStruct->NVIC_IRQChannel & (uint8_t)0x1F); 开启中断
}
else
{
/* Disable the Selected IRQ Channels -------------------------------------*/
NVIC->ICER[0] = (uint32_t)0x01 << (NVIC_InitStruct->NVIC_IRQChannel & (uint8_t)0x1F);
}
}
打开startup_stm32f0xx.s 详细分析
PUBLIC __vector_table
DATA
__vector_table
DCD sfe(CSTACK)
DCD Reset_Handler ; Reset Handler
DCD NMI_Handler ; NMI Handler
DCD HardFault_Handler ; Hard Fault Handler
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD SVC_Handler ; SVCall Handler
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD PendSV_Handler ; PendSV Handler
DCD SysTick_Handler ; SysTick Handler
; External Interrupts
DCD WWDG_IRQHandler ; Window Watchdog
DCD PVD_VDDIO2_IRQHandler ; PVD and VDDIO2 through EXTI Line detect
DCD RTC_IRQHandler ; RTC through EXTI Line
DCD FLASH_IRQHandler ; FLASH
DCD RCC_CRS_IRQHandler ; RCC and CRS
DCD EXTI0_1_IRQHandler ; EXTI Line 0 and 1 //向量表中外部中断 0 1，标号EXTI0_1_IRQHandler
DCD EXTI2_3_IRQHandler ; EXTI Line 2 and 3
DCD EXTI4_15_IRQHandler ; EXTI Line 4 to 15
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Default interrupt handlers.
;;
THUMB
PUBWEAK Reset_Handler
SECTION .text:CODE:NOROOT:REORDER(2) //SECTION .text:CODE:REORDER(2) modify bu hxc 2014.11.9
Reset_Handler
LDR R0, =SystemInit
BLX R0
LDR R0, =__iar_program_start
BX R0
PUBWEAK NMI_Handler
SECTION .text:CODE:NOROOT:REORDER(1)
NMI_Handler
B NMI_Handler
PUBWEAK HardFault_Handler
SECTION .text:CODE:NOROOT:REORDER(1)
HardFault_Handler
B HardFault_Handler
PUBWEAK SVC_Handler
SECTION .text:CODE:NOROOT:REORDER(1)
SVC_Handler
B SVC_Handler
PUBWEAK PendSV_Handler
SECTION .text:CODE:NOROOT:REORDER(1)
PendSV_Handler
B PendSV_Handler
PUBWEAK SysTick_Handler
SECTION .text:CODE:NOROOT:REORDER(1)
SysTick_Handler
B SysTick_Handler
PUBWEAK WWDG_IRQHandler
SECTION .text:CODE:NOROOT:REORDER(1)
WWDG_IRQHandler
B WWDG_IRQHandler
PUBWEAK PVD_VDDIO2_IRQHandler
SECTION .text:CODE:NOROOT:REORDER(1)
PVD_VDDIO2_IRQHandler
B PVD_VDDIO2_IRQHandler
PUBWEAK RTC_IRQHandler
SECTION .text:CODE:NOROOT:REORDER(1)
RTC_IRQHandler
B RTC_IRQHandler
PUBWEAK FLASH_IRQHandler
SECTION .text:CODE:NOROOT:REORDER(1)
FLASH_IRQHandler
B FLASH_IRQHandler
PUBWEAK RCC_CRS_IRQHandler
SECTION .text:CODE:NOROOT:REORDER(1)
RCC_CRS_IRQHandler
B RCC_CRS_IRQHandler
PUBWEAK EXTI0_1_IRQHandler
SECTION .text:CODE:NOROOT:REORDER(1)
EXTI0_1_IRQHandler
B EXTI0_1_IRQHandler //外部中断 0 1 跳转地址
打开stm32f0xx_it.c
/******************************************************************************/
/* STM32F0xx Peripherals Interrupt Handlers */
/* Add here the Interrupt Handler for the used peripheral(s) (PPP), for the */
/* available peripheral interrupt handler‘s name please refer to the startup */
/* file (startup_stm32f0xx.s). */
/******************************************************************************/
/**
* @brief This function handles External line 0 to 1 interrupt request.
* @param None
* @retval None
*/
void EXTI0_1_IRQHandler(void)
{
if(EXTI_GetITStatus(EXTI_Line0) != RESET)
{
/* Toggle LED4 */ //中断处理内容
STM_EVAL_LEDToggle(LED4);
/* Clear the EXTI line 0 pending bit */
EXTI_ClearITPendingBit(EXTI_Line0); //退出前清除中断标志，以便接收下次中断
}
}
打开stm32f0xx.h
WWDG_IRQn = 0, /*!< Window WatchDog Interrupt */
PVD_VDDIO2_IRQn = 1, /*!< PVD and VDDIO2 supply comparator through EXTI Line detect Interrupt */
RTC_IRQn = 2, /*!< RTC through EXTI Line Interrupt */
FLASH_IRQn = 3, /*!< FLASH Interrupt */
RCC_CRS_IRQn = 4, /*!< RCC and CRS Interrupts */
EXTI0_1_IRQn = 5, /*!< EXTI Line 0 and 1 Interrupts */ 在这IRQ号=5
EXTI2_3_IRQn = 6, /*!< EXTI Line 2 and 3 Interrupts
STM32F072B-DISCO 深入研究