nRF51822之BootLoader

nRF51822之BootLoader

一)nRF51822程序加载顺序

1)SoftDevice加载;
2)SoftDevice初始化蓝牙协议栈;
3)SoftDevice检查0x10001014处是否保存有有效的BootLoader地址, 如果不是跳转到0x14000处的APP执行,流程结束.
4)SoftDevice跳转到BootLoader
5)BootLoader进行他的业务处理工作;
6)BootLoader跳转到0x14000处的APP执行,流程结束.

二)实现步骤

1)修改SoftDivice.hex
看NRF_UICR_Type结构,有一个BOOTLOADERADDR字段,  这个就是指向的BootLoader地址

typedef struct {/*!< UICR Structure*/
  __IO uint32_t  CLENR0; /*!< Length of code region 0.*/
  __IO uint32_t  RBPCONF; /*!< Readback protection configuration.*/
  __IO uint32_t  XTALFREQ; /*!< Reset value for CLOCK XTALFREQ register.*/
  __I  uint32_t  RESERVED0;
  __I  uint32_t  FWID;     /*!< Firmware ID.*/
  __IO uint32_t  BOOTLOADERADDR;/*!< Bootloader start address.*/
} NRF_UICR_Type;

默认情况下,SoftDivice.hex没有指定BootLoader地址;
我们需要在SoftDivice.hex中插入一行

:0410140000300100A7

参考HEX文件说明

这里修改0x10001014地址的数据为"00300100"就是0x13000, 这个地址根据BootLoader的实际位置修改.

2)编写BootLoader
BootLoader本身是一个普通的程序,只是在跳转到APP执行时需要特殊处理

static void interrupts_disable(void) {
   uint32_t interrupt_setting_mask = NVIC->ISER[0];
   for (uint8_t irq=0; irq < 32; irq++) {
      if (interrupt_setting_mask & (1 << irq)) {
         NVIC_DisableIRQ((IRQn_Type) irq);
      }
   }
}

__asm void StartApplication(uint32_t start_addr){
    LDR   R2, [R0]               ; Get App MSP.
    MSR   MSP, R2                ; Set the main stack pointer to the applications MSP.
    LDR   R3, [R0, #0x00000004]  ; Get application reset vector address.
    BX    R3                     ; No return - stack code is now activated only through SVC and plain interrupts.
    ALIGN
}

/**
 * 跳转到APP执行
 */
static void bootloader_app_start(uint32_t app_addr) {
   sd_softdevice_disable();
   interrupts_disable();
   sd_softdevice_forward_to_application();
   StartApplication(app_addr);
}

把BootLoader写入我们上面定义的地址 0x13000

3)编写APP
APP跟没有BootLoader时是一样的,依然放在 0x14000 处