串口闪存和PIC32的新手问题

嗨，我正在执行一个带有PIC32 MX27的系统和一个来自Simon的串行SLC NAND闪存。为了让我检查通信（SPI）是否正确，我用一个“读ID”命令（0x9F）运行了一个测试，看我是否从Flash中得到一个答案（这是一个2字节的答案：0x2C和0x36，用于微米和类型）。分别为Flash）。所以，我连接了我的逻辑分析仪来检查SPI信号，我注意到，尽管闪存的答案是正确的，但它并没有按照内存数据表中的精确脉冲序列。它包含了一个奇怪的时间间隔。我附上2张图片和我的代码。第一张图片描绘了在Flash数据表中描述的命令0x9F所需的时间图。第二幅图描绘了来自我的逻辑分析仪的实际信号。正如您将注意到的，在开始之前，命令在FLASH应答之前被连续发送2次（而不是一次）。还有时钟脉冲之间的时间间隔，我不明白。SCK脉冲不应该像数据表一样是一个大脉冲序列吗？我相信我一定在代码中写了一些错误的东西。谢谢你的时间。



      以下为原文

    Hi, I am implementing a system with a PIC32MX274 and a serial SLC nand flash from micron.
In order for me to check if the communication (SPI) is correct I ran a test with a "Read ID" command (0x9F) to see if I get an answer from the flash (which is a 2-byte answer: 0x2C and 0x36, for micron and type of flash respectively). So, I connected my logic analyzer to check the SPI signals and I noticed that although the answer from the flash memory is correct, it doesn't  follow the exact pulse sequence as in the memory's datasheet. It contains a strange time gap.  I attach 2 pictures and my code. The first picture depicts the desired time figure for the command 0x9F depicted in the flash datasheet . The second picture depicts the actual signals from my logic analyzer. As you will notice, at the beginning the command is being sent 2 times in a  row (instead of one) before the flash answers . Also there is a time gap between clock pulses which I don't understand. Shouldn't the SCK pulses be one big pulse train without interruptions like the one in datasheet?  I believe that I must have written something something the wrong way in the code.

Thank you for your time.

void pinRemap(void){
    //==============================remap pins==================================
     TRISCbits.TRISC1 = 1; // set this as an input for MISO
     TRISAbits.TRISA1 = 0; // set this as an output for MOSI
     TRISAbits.TRISA7 = 0; // set this as an output for CS
     TRISAbits.TRISA9 = 0; // LED output
     TRISBbits.TRISB15 = 0; // set this as an output for SCK
     
    CFGCONbits.IOLOCK = 0; // unlock
    RPC1R = 0x06; // re-map SDI2(MISO2) to RC1 pin
    RPA1R = 0x04; // re-map SDO2(MOSI2) to RA1 pin
    CFGCONbits.IOLOCK = 1; // lock
}


void spiInit(void){
    //==========================SPI INITIALIZATION=============================
   
    SPI2CONbits.ON = 0 ; // SPI OFF
    IEC1bits.SPI2EIE = 0; // Disable SPI interrupt
    IEC1bits.SPI2RXIE = 0; // Disable SPI interrupt
    IEC1bits.SPI2TXIE = 0; // Disable SPI interrupt
   
   
    SPI2STATbits.SPIROV = 0; // Clear overflow flag
    SPI2BUF = 0; // Clear the receive buffer
    SPI2BRG = 8; // FSCK = 2.5MHz
    //SPI2CONbits.MODE16 = 1;
    SPI2CONbits.ENHBUF = 1;
    SPI2CON = 0; // reset SPI2CON to be sure and then initialize it
    SPI2CONbits.MCLKSEL = 0; // PB_CLK used by BRG
    SPI2CONbits.MSSEN = 1; // SS pin automatically driven
    SPI2CONbits.CKP = 0; // SCK IDLE = LOW (CPOL)
    SPI2CONbits.CKE = 1; // Output data changes from idle to active SCK
    SPI2CONbits.MSTEN = 1; // Master Mode
}

int main(void) {
  
    unsigned char i = 0;
    ANSELA = 0; // Disable analog mode inputs
   
    pinRemap(); // remap pins
    spiInit(); // initialize spi
   
    while(1){
      
        SPI2CONbits.ON = 1; //Enable SPI
     
        SPI2BUF = 0x9F; // Write command to buffer
        SPI2BUF = 0x00;
        while(!SPI2STATbits.SPIRBF); // Wait until receive buffer is full
        i = SPI2BUF; // read the answer from the flash which is 0x2C and 0x36
        
        SPI2CONbits.ON = 0; // Disable SPI2
        SPI2BUF = 0; // Clear Buffer
    }
   
    return 0;
}

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