硬件环境：NXP 1788

软件环境：KEIL

实现过程：上面说了我准备了两个程序，就用裸机版的代码说一下实现流程。带操作系统的原理都是一样的。只是多创建几个任务而已。USB_HOST实现IAP升级，总的思路就是：复制bin文件到U盘->目标板断电，插上U盘->目标板上电，进入升级->运行升级程序。其实可以更具体，比如说设置升级标志或者按键。

拿到一个程序先从main开始，直接贴代码，说一大堆废话有什么用。

int main()
{
  int32_t  rc;
 uint32_t  numBlks,blkSize;
 uint8_t inquiryResult[INQUIRY_LENGTH];

SystemInit();

UART_Init(57600);         
   Host_Init();              
    rc =Host_EnumDev();      
    if (rc ==OK) {
  
       rc = MS_Init( &blkSize, &numBlks, inquiryResult );
       if (rc == OK) {
           rc = FAT_Init();  
           if (rc == OK) {
               Bin_Read();   
           } else {
               return (0);
           }
       } else {
           return (0);
       }
    } else{       
       return (0);
    }
   while(1);
}

下面分模块说一下， 前面的硬件初始化函数很简单，USB设备枚举和FAT文件系统NXP官网上都有，只需改硬件接口，Host_Init函数如下：

void  Host_Init(void)
{
 uint32_t HostBaseAddr;

LPC_SC->PCONP   |=0x80000000;
   LPC_USB->OTGClkCtrl   =0x00000019; 
    while((LPC_USB->OTGClkSt & 0x00000019) != 0x19);
 
 LPC_USB->StCtrl =0x1;

LPC_IOCON->P0_29 &= ~(0x07UL << 0);
   LPC_IOCON->P0_30 &= ~(0x07UL << 0);
   LPC_IOCON->P1_28 &= ~(0x07UL << 0);
   LPC_IOCON->P1_29 &= ~(0x07UL << 0);

LPC_IOCON->P0_29 |= 0x01UL <<0;                                   
   LPC_IOCON->P0_30 |= 0x01UL <<0;                                   
   LPC_IOCON->P1_28 |= 0x01UL <<0;                                   
   LPC_IOCON->P1_29 |= 0x01UL <<0;                                   //  P1.29 --USB_SDA1     
   PRINT_Log("Initializing HostStack\n");

HostBaseAddr = HOST_BASE_ADDR;

Hcca      = (volatile HCCA      *)(HostBaseAddr+0x000);
   TDHead    = (volatile HCTD      *)(HostBaseAddr+0x100);
   TDTail    = (volatile HCTD      *)(HostBaseAddr+0x110);
   EDCtrl    = (volatile HCED      *)(HostBaseAddr+0x120);
   EDBulkIn   =(volatile HCED      *)(HostBaseAddr+0x130);
   EDBulkOut  = (volatile HCED      *)(HostBaseAddr+0x140);
   TDBuffer   =(volatile  uint8_t *)(HostBaseAddr+0x150);
   FATBuffer  = (volatile  uint8_t*)(HostBaseAddr+0x1D0);
    UserBuffer =(volatile  uint8_t*)(HostBaseAddr+0x1000);

Host_EDInit(EDCtrl);
   Host_EDInit(EDBulkIn);
   Host_EDInit(EDBulkOut);
   Host_TDInit(TDHead);
   Host_TDInit(TDTail);
   Host_HCCAInit(Hcca);

Host_DelayMS(50);               
   LPC_USB->Control      = 0;   
   LPC_USB->ControlHeadED =0;   
   LPC_USB->BulkHeadED   = 0;   
   
   
   LPC_USB->CommandStatus = OR_CMD_STATUS_HCR;
   LPC_USB->FmInterval   = DEFAULT_FMINTERVAL;

LPC_USB->Control  = (LPC_USB->Control &(~OR_CONTROL_HCFS)) | OR_CONTROL_HC_OPER;
   LPC_USB->RhStatus =OR_RH_STATUS_LPSC;       
   
   LPC_USB->HCCA = (uint32_t)Hcca;
   LPC_USB->InterruptStatus |=LPC_USB->InterruptStatus;

LPC_USB->InterruptEnable  = OR_INTR_ENABLE_MIE|
                        OR_INTR_ENABLE_WDH |
                        OR_INTR_ENABLE_RHSC |
                        OR_INTR_ENABLE_UE;

NVIC_EnableIRQ(USB_IRQn);              
 NVIC_SetPriority (USB_IRQn,0);

PRINT_Log("Host Initialized\n");
}

这段主要是USB引脚配置和USB主机初始化。Bin_Read()函数如下：

void  Bin_Read(void)
{
     int32_t  fdr;
     uint32_t  bytes_read,writelen;
     uint32_t dstaddr;
     SelSector(APP_START_SECTOR,APP_END_SECTOR);        //选择扇区
     EraseSector(APP_START_SECTOR,APP_END_SECTOR);                         
     BlankCHK(APP_START_SECTOR,APP_END_SECTOR);                            
     SelSector(APP_START_SECTOR,APP_END_SECTOR);    
     PRINT_Log("\r\nstart file operations...\r\n");

fdr = FILE_Open(FILENAME_R, RDONLY);
    if (fdr >0) {
       PRINT_Log("Reading from %s...\n", FILENAME_R);
  for(writelen=0;writelen<(APP_END_ADDR-APP_START_ADDR)/1024;writelen++)
   {
    bytes_read =FILE_Read(fdr, UserBuffer,MAX_BUFFER_SIZE);           
    dstaddr=  (uint32_t)(APP_START_ADDR +(writelen)*1024);//dst address.  
   SelSector(APP_START_SECTOR,APP_END_SECTOR);    
   RamToFlash(dstaddr,(uint32_t)UserBuffer, 1024);
   Compare(dstaddr, (uint32_t)UserBuffer, 1024);
   }  
  // printf("%x",writelen);
  PRINT_Log("\r\n write filesuccessful\r\n");
   SCB->VTOR  =APP_START_ADDR;                                             
   ExceuteApplication();                                                      
   FILE_Close(fdr);                                                            
    } else{
       PRINT_Log("\r\n write file failed\r\n");
    }
}

上面的代码可以分为两部分：1.从U盘读取bin文件2.IAP功能。先说IAP部分，IAP实现方法有UART,GPRS,USB等方式。要进行IAP设计，先划分FLASH扇区。LPC1788的FLASH划分如下：

 

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