ArduPilot存储管理 Storage EEPROM Flash

AP_HAL::Storage
此类可以应用于所有平台。PX4v1平台支持8k的EEPROM，Pixhawk平台支持16k的FRAM铁电存储器

存储大小定义：libraries/AP_HAL/AP_HAL_Boards.h中HAL_STORAGE_SIZE

The DataFlash library
DataFlash是用来存储日志的。日志有固定的格式，固定的日志头和日志包头

//`日志头格式`// structure used to define logging formatstruct LogStructure {    uint8_t msg_type;    uint8_t msg_len;    const char name[5];    const char format[16];    const char labels[64];};//`日志包头`#define LOG_PACKET_HEADER          uint8_t head1, head2, msgid;

日志举例
libraries/DataFlash/examples/DataFlash_test/DataFlash_test.cpp

struct PACKED log_Test {    LOG_PACKET_HEADER;    uint16_t v1, v2, v3, v4;    int32_t  l1, l2;};

日志是以文件的形式存储到microSD card，可以直接拔出SD卡拷贝到PC

每个页首都有“日志文件的编号”和“日志文件的页号”。当用户下载日志时，非常有用

bool DataFlash_Block::WritePrioritisedBlock(const void *pBuffer, uint16_t size,    bool is_critical){    // is_critical is ignored - we're a ring buffer and never run out    // of space.  possibly if we do more complicated bandwidth    // limiting we can reservice bandwidth based on is_critical    if (!CardInserted() || !log_write_started || !_writes_enabled) {        return false;    }    if (! WriteBlockCheckStartupMessages()) {        return false;    }    while (size > 0) {//while 判断条件         uint16_t n = df_PageSize - df_BufferIdx;        if (n > size) {            n = size;        }        if (df_BufferIdx == 0) {            // if we are at the start of a page we need to insert a            // page header            if (n > df_PageSize - sizeof(struct PageHeader)) {                n = df_PageSize - sizeof(struct PageHeader);            }            struct PageHeader ph = { df_FileNumber, df_FilePage };// df_FileNumber, df_FilePage 初始化中从SD卡中读回  add 0xff            BlockWrite(df_BufferNum, df_BufferIdx, &ph, sizeof(ph), pBuffer, n);//df_BufferNum 缓存区编号 0/1            df_BufferIdx += n + sizeof(ph);        } else {            BlockWrite(df_BufferNum, df_BufferIdx, NULL, 0, pBuffer, n);            df_BufferIdx += n;        }        size -= n;        pBuffer = (const void *)(n + (uintptr_t)pBuffer);        if (df_BufferIdx == df_PageSize) {            FinishWrite();            df_FilePage++;        }    }    return true;}

日志按块读写
用户需要设置page大小512 byte，当写满一页以后告诉芯片复制一页

日志本身是通过DataFlash_File.cpp写到SD卡，还提供了DataFlash_Empty.cpp的块设备读写接口，下面是应用铁电的读写实例

//缓冲区bufferstatic uint8_t buffer[2][DF_PAGE_SIZE]; void DataFlash_Flash::Init(const struct LogStructure *structure, uint8_t num_types){    DataFlash_Backend::Init(structure, num_types);    if (flash_fd == 0) {        flash_fd = open(MTD_LOG_FILE, O_RDWR, 0777);        if (flash_fd == -1) {            printf("DataFlash_Flash init failed\n");        }    }    df_PageSize = DF_PAGE_SIZE; //页大小    df_NumPages = DF_NUM_PAGES - 1; //页数量}//读取flash数据到buffervoid DataFlash_Flash::PageToBuffer(unsigned char BufferNum, uint16_t PageAdr){    PageAdr -= 1;    uint16_t ofs = PageAdr * DF_PAGE_SIZE;    memset(buffer[BufferNum], 0, DF_PAGE_SIZE);    if (lseek(flash_fd, ofs, SEEK_SET) != ofs) {        printf("PageToBuffer lseek err.\n");        return;    }    if (read(flash_fd, buffer[BufferNum], DF_PAGE_SIZE) != DF_PAGE_SIZE)    {        printf("PageToBuffer read err.\n");        return;    }}//记录需要写入flash的页地址和缓冲区编号void DataFlash_Flash::BufferToPage (unsigned char BufferNum, uint16_t PageAdr, unsigned char wait){       PageAdr -= 1;    uint16_t ofs = PageAdr * DF_PAGE_SIZE;    if(flash_fd < 0) return;    if (lseek(flash_fd, ofs, SEEK_SET) != ofs) {        printf("BufferToPage lseek err.\n");        return;    }    if (::write(flash_fd, &buffer[BufferNum], DF_PAGE_SIZE) != DF_PAGE_SIZE)    {        printf("BufferToPage write err.\n");        return;    }}//数据写入缓冲区void DataFlash_Flash::BlockWrite(uint8_t BufferNum, uint16_t IntPageAdr,                                const void *pHeader, uint8_t hdr_size,                                const void *pBuffer, uint16_t size){   if (!_writes_enabled) {        return;    }    memset(&buffer[BufferNum][IntPageAdr], 0, size+hdr_size);    if (hdr_size) {        memcpy(&buffer[BufferNum][IntPageAdr],               pHeader,               hdr_size);    }    memcpy(&buffer[BufferNum][IntPageAdr+hdr_size],           pBuffer,           size);}//从缓冲区读取数据bool DataFlash_Flash::BlockRead(uint8_t BufferNum, uint16_t IntPageAdr, void *pBuffer, uint16_t size){    memset(pBuffer, 0, size);    memcpy(pBuffer, &buffer[BufferNum][IntPageAdr], size);    return true;}