关于STM32如何在应用程序中跳转到ISP固件升级

什么是ISP

ISP是STM32单片机使用串口下载升级程序的下载协议。通过上电检测Boot0和Boot1的电平从不同的位置运行程序。

本文实现的功能

通过在用户的应用程序中触发更新标志，将程序跳转到System memory中去执行32的ISP固件升级代码

上代码

/**
 * Function to perform jump to system memory boot from user application
 *
 * Call function when you want to jump to system memory
 */
void JumpToBootloader(void) {
	void (*SysMemBootJump)(void);

//	volatile uint32_t addr = 0x1FFFEC00;	//System memory首地址，此地址为stm32f030f4的首地址，
	volatile uint32_t addr = 0x1FFFF000; //此地址为STM32F103RE的地址，其余型号地址自行在数据手册中进行查找
	 
	/**
	 * Step: Disable RCC, set it to default (after reset) settings
	 *       Internal clock, no PLL, etc.
	 */
#if defined(USE_HAL_DRIVER)
	HAL_RCC_DeInit();
#endif /* defined(USE_HAL_DRIVER) */
#if defined(USE_STDPERIPH_DRIVER)
	RCC_DeInit();
#endif /* defined(USE_STDPERIPH_DRIVER) */
	
	/**
	 * Step: Disable systick timer and reset it to default values
	 */
	SysTick->CTRL = 0;
	SysTick->LOAD = 0;
	SysTick->VAL = 0;

	/**
	 * Step: Disable all interrupts
	 */
	__disable_irq();
	
	/**
	 * Step: Remap system memory to address 0x0000 0000 in address space
	 *       For each family registers may be different. 
	 *       Check reference manual for each family.
	 *
	 *       For STM32F4xx, MEMRMP register in SYSCFG is used (bits[1:0])
	 *       For STM32F0xx, CFGR1 register in SYSCFG is used (bits[1:0])
	 *       For others, check family reference manual
	 */
	//Remap by hand... {
#if defined(STM32F4)
	SYSCFG->MEMRMP = 0x01;
#endif
#if defined(STM32F0)
	SYSCFG->CFGR1 = 0x01;
#endif
	//} ...or if you use HAL drivers
	//__HAL_SYSCFG_REMAPMEMORY_SYSTEMFLASH();	//Call HAL macro to do this for you
	
	/**
	 * Step: Set jump memory location for system memory
	 *       Use address with 4 bytes offset which specifies jump location where program starts
	 */
	SysMemBootJump = (void (*)(void)) (*((uint32_t *)(addr + 4)));
	
	/**
	 * Step: Set main stack pointer.
	 *       This step must be done last otherwise local variables in this function
	 *       don't have proper value since stack pointer is located on different position
	 *
	 *       Set direct address location which specifies stack pointer in SRAM location
	 */
	__set_MSP(*(uint32_t *)addr);
	
	/**
	 * Step: Actually call our function to jump to set location
	 *       This will start system memory execution
	 */
	SysMemBootJump();
	
	/**
	 * Step: Connect USB<->UART converter to dedicated USART pins and test
	 *       and test with bootloader works with STM32 Flash Loader Demonstrator software
	 */
}

结果

本文已在STM32F103RE上进行验证，亲测可用，其余单片机自行验证。
但是stm32f030f4上不能实现，具体原因尚在寻找，若有大神知道敬请指教。

STM32F103RE验证源码下载

https://download.csdn.net/download/cooper1024/11139789

测试过程

• 1、将源码下载到片子中
• 2、重启程序通过串口调试助手可以看到程序中的打印。

3、关闭串口调试助手，打开Flymcu，配置串口下载文件，选择文件点击“开始编程”。发现程序直接就下载片子中去了。可见程序已经进入ISP固件升级了。此方法省去了用Boot0和Boot1的高低电平进入ISP固件升级模式的操作。