AT45DB641从flash读取数据函数，要求可自定义页和地址和数据长度

好的，以下是一个C语言的AT45DB641从flash读取数据的函数，其中页、地址和数据长度都可以自定义：

#include <SPI.h>

#define AT45DB641_PAGE_SIZE 264
#define AT45DB641_PAGE_COUNT 8192
#define AT45DB641_BLOCK_SIZE 264

void readFromFlash(uint16_t page, uint16_t address, uint16_t length, uint8_t* buffer) {
  uint32_t start_address = ((uint32_t)page * AT45DB641_PAGE_SIZE + address) % (AT45DB641_PAGE_SIZE * AT45DB641_PAGE_COUNT);
  uint16_t remaining_length = length;
  uint16_t current_address = start_address;
  uint8_t* current_buffer = buffer;

  while (remaining_length > 0) {
    uint16_t current_length = min(remaining_length, AT45DB641_BLOCK_SIZE - (current_address % AT45DB641_BLOCK_SIZE));
    uint8_t read_command[] = {0x0B, (current_address >> 16) & 0xFF, (current_address >> 8) & 0xFF, current_address & 0xFF, 0x00, 0x00, 0x00};
    SPI.beginTransaction(SPISettings(10000000, MSBFIRST, SPI_MODE0));
    digitalWrite(SS, LOW);
    SPI.transfer(read_command, sizeof(read_command));
    SPI.transfer(current_buffer, current_length);
    digitalWrite(SS, HIGH);
    SPI.endTransaction();
    remaining_length -= current_length;
    current_address += current_length;
    current_buffer += current_length;
  }
}

这个函数首先计算出从哪个地址开始读取数据，然后循环读取数据块直到读取完整个数据长度。在循环中，它会计算出当前块的长度（不超过264字节），构造读取命令，发送命令和数据，然后更新剩余的数据长度、地址和缓冲区指针。注意，这个函数需要使用SPI库进行通信，需要先调用SPI.begin()初始化SPI，并将AT45DB641的片选引脚连接到Arduino的SS引脚上。