How to read&Write External Flash with NRF52832 SPI0 ?

[Larkin]

Hi,

My problems are as follows:

SDK :nRF5_SDK_15.0.0_a53641a.

IDE:MDK 5.2.6

Chip:nrf52832  SPI0

External Flash :W25Q64

Now ,I can read the chip ID  correctly ,but when I transfer 256 bytes to External Flash ,as if only can write 251 bytes successfully, 

• Is there something wrong with my code oprtion?
  Thank  you!

• ...

[Larkin]

void SPI_FLASH_PageWrite(uint8_t* pBuffer, uint32_t WriteAddr, uint16_t NumByteToWrite)

{

    uint16_t  len = NumByteToWrite;

    uint16_t len_cut = 0;  

    uint32_t  addr = WriteAddr;

    uint8_t   *pic_point_w = pBuffer;

SPI_FLASH_WriteEnable();

   Flash_Delsy_ms(500);

    do {

 memset(FLASH_SPI_Tx_Buf,0x00,255);

        FLASH_SPI_Tx_Buf[0] = WRITE;

        FLASH_SPI_Tx_Buf[1] = (uint8_t)((addr & 0x00FF0000) >> 16);

        FLASH_SPI_Tx_Buf[2] = (uint8_t)((addr & 0x0000FF00) >> 8);

        FLASH_SPI_Tx_Buf[3] = (uint8_t)  addr ;

        len_cut = (len >= (0xFB - 4)) ? (0xFB) : (len + 4);

        memcpy(&FLASH_SPI_Tx_Buf[4], pic_point_w, (len_cut - 4));

        SPI_FLASH_CS_LOW;

        FLASH_spi_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spi_transfer(&FLASH_spi, FLASH_SPI_Tx_Buf,len_cut, FLASH_SPI_Rx_Buf, len_cut));

         while(FLASH_spi_xfer_done == false);

        SPI_FLASH_CS_HIGH;

        addr += (len_cut - 4);

        pic_point_w += (len_cut - 4);

 len -= (len_cut - 4);

   Flash_Delsy_ms(10);

       } while(len > 0);

    SPI_FLASH_CS_HIGH;

    SPI_FLASH_WaitForWriteEnd();

}