Micro SD SPI无法高速工作

这可能是你想发表的。你看到了：触发防火墙的表达式。



      以下为原文

    It's probably what you're trying to post.
 
Have you seen: Expressions which trigger the firewall 
 

我将张贴一位一次…嗨，我正在阅读文件从一个新的微型SD卡使用PIC32启动器套件和多媒体扩展板II（MEB II）。我正在读取一个文件并显示在一个128×32的RGB LED显示屏上。它运行良好（计划优化更多的速度）使用波特率低于700千赫，但当我把速度改变到上面的任何初始化后，它被卡住（我会强调它在代码-见SPI2Read（））。文件说要初始化卡在400千赫，我这样做。我已经证实波特率确实在一个范围内转换。这些信号看起来很干净，而且相当平直。我的代码张贴在下面，我注意到它被卡在哪里。它只是不断尝试发送，好像卡没有接收或发送任何东西回来。我有什么遗漏了吗？MEB II板上有什么东西会弄脏这个吗？如果有人知道这个，我会很感激的。相关代码如下：SPI.cFr.c



      以下为原文

    I'll post one bit at a time...
 
Hi,  I'm reading files from a new Micro SD card using the PIC32 Starter Kit and Multimedia Expansion Board II (MEB II).  I'm reading a file and displaying it on a 128 x 32 RGB LED display.  It's working fine (planning on optimizing for more speed) using a baud rate below ~700KHz, but when I change the speed to anything above that after initialization, it gets stuck (I'll highlight it in the code - see SPI2Read()).  The documentation says to initialize the card at 400KHz, which I do.  I've confirmed that the baud rate does switch with a scope.  The signals look clean and fairly square.  My code is posted below and I note where it gets stuck.  It just keeps trying to transmit as if the card isn't receiving or sending anything back.  Is there something I'm missing?  Is there something on the MEB II board that could mess this up?  If anyone has a clue about this, I would appreciate it.  Relevant code posted below:
 
spi.c

 
void InitSPI(void)
{
    int rData, i;
    IEC4CLR = 0x1c000; // disable all interrupts
    SPI2CON = 0; // Stops and resets the SPI2.
    rData = SPI2BUF;// clears the receive buffer
    IFS4CLR = 0x1c000; // clear any existing event
    IPC35CLR = 0x1f000000; // clear the priority
    IPC35SET = 0x0d000000; // Set IPL=3, Subpriority 1
    SPI2BRG = 124;// buad rate = PBCLK2 (100MHz) / ((SPI2BRG + 1) / 2) or 400KHz
    SPI2STATCLR = 0x40;// clear the Overflow
    SPI2CON = 0x8220;// SPI ON, 8 bits transfer, SMP=1, Master mode
    // from now on, the device is ready to transmit and receive data
}
 
void ChangeSPISpeed(unsigned int newspeed)
{
    DESELECT
    SPI2CON = 0; // Stops and resets the SPI2.
    SPI2BRG = 4; // 10 MHz - I've tried other speeds
    SPI2CON = 0x8220;// SPI ON, 8 bits transfer, SMP=1, Master mode
    SELECT
}
 
unsigned char SPI2_Read(void)
{
   SPI2BUF = 0xff;
    while (!SPI2STATbits.SPITBE); // *********** This is where it gets stuck at baud rate > ~700KHz ***********
    return SPI2BUF;
}
 
// Transmit a byte via SPI channel 2
void SPI2_Xmit( unsigned char data )
{
 SPI2BUF = (unsigned short)data; // place the data in the buffer
    while (!SPI2STATbits.SPITBE); // wait until the transmit buffer is empty (data has been sent)
    while (SPI2STATbits.SPIRBE); // wait until a byte is received
    crap = SPI2BUF; // byte received during transmit is junk
}
 
// Send a command packet
unsigned char Cmd_Send (
 unsigned char cmd,  /* Command unsigned char */
 unsigned int arg,  /* Argument */
 unsigned char crc  /* CRC */
)
{
 if (cmd & 0x80) // if the command is an ACMD (application command), send CMD55 first
    {
  cmd &= 0x7F; // all ACMDs have the 7th bit set, so mask it out
  r = Cmd_Send(CMD55, 0, 0xff); // send CMD55 first
  if (r > 1) return r; // response should be 0 or 1
 }
    DESELECT
    SELECT
    while(SPI2_Read() != 0xff); // give the SD card some time to prepare for the next instruction and flush the bytes or something
    Timer1 = 10;
    while (Timer1);
 /* Send command packet */
 SPI2_Xmit(cmd);           /* Command */
 SPI2_Xmit((unsigned char)(arg >> 24));  /* Argument[31..24] */
 SPI2_Xmit((unsigned char)(arg >> 16));  /* Argument[23..16] */
 SPI2_Xmit((unsigned char)(arg >> 8));  /* Argument[15..8] */
 SPI2_Xmit((unsigned char)arg);    /* Argument[7..0] */
 SPI2_Xmit(crc);
    t = 10;
    do
    {
        r = SPI2_Read();
    }
    while ((r & 0x80) && --t); // read until bit 7 is not set
    return r;
}
 

 
file.c

//test

嗨，你有PIC32启动套件：PIC32 MZ EF启动器套件？当做



      以下为原文

    Hi ,
Which PIC32 starter kit do you have : PIC32MZ EF starter kit ?
Regards
 

是的，这是一个PIC32 MZ EF非密码启动套件。200 MHz PIC32 MZ2048 EFH CPU



      以下为原文

    Yes, it's a PIC32MZ EF non-crypto Starter Kit.  200MHz PIC32MZ2048EFH CPU

伟大的。。。试图上传.c文件，我得到“访问拒绝”。我能在这个网站上做什么？



      以下为原文

    Great... trying to upload .c files and I get "Access Denied".  What CAN I do on this site?

嗨，哪种文档？当做



      以下为原文

    Hi,

Which documentation ?
Regards

哪些文件？符合SD标准。卡在DO开模模式下启动，所以速度必须限制直到初始化。



      以下为原文

   
Which documentation ?
Regards

The SD standard. The card starts in open-drain mode on DO, so the speed has to be limited until initialised.

可能的是，如果卡仍然在开式排水模式，这将解释症状…



      以下为原文

    Possibly if the card is STILL in open-drain mode, that would explain the symptoms ...
 

重复，最好继续这里HTTP//www. MICCHIP.COM/FUMMS/M1010106ASPX



      以下为原文

    Duplicate, better continue here
http://www.microchip.com/forums/m1010106.aspx
 

你使用空闲时钟（CKP）0还是1？通常情况下，它将是SMP＝1，CKE＝0，CKP＝1或SMP＝0，CKE＝1，CKP＝0。



      以下为原文

    Are you using idle clock (CKP) 0 or 1?
Normally it would be either SMP=1,CKE=0,CKP=1 OR  SMP=0,CKE=1,CKP=0

我会检查一下，但是我会回应Atttp://www. McCHIP.COM/FUMMS/M1010106ASPX。



      以下为原文

    Lurch, I will check, but I will respond at http://www.microchip.com/forums/m1010106.aspx.
 
Sorry for the duplicate, it was giving me a fit with "Access Denied".

我发现有必要允许更长的时间来应对。这里的延迟很大程度上取决于SPI速度。此外，您应该理想地读取SD卡的能力，以检查它可以处理您想要使用的比特率。



      以下为原文

    t = 10;
do
{
r = SPI2_Read();
}
while ((r & 0x80) && --t); // read until bit 7 is not set
return r;

I found it necessary to allow much longer for responses. The delay here is very much dependent on SPI speed. Also, you should ideally read the capabilities of the SD card to check that it can handle the the bit rate you want to use.

嘿，我发现问题了，孩子，我觉得自己像个白痴！这是一个定时器中断，我必须刷新一个小显示器。在较低的频率下，中断可以在接收缓冲器溢出并导致问题之前完成。谢谢你的提示。在论坛上蠕动；



      以下为原文

    Hey, I found the problem and, boy, do I feel like an idiot!  It was a timer interrupt that I have to refresh a small display.  At lower frequencies, the interrupt could finish before the receive buffer would overflow and cause problems.  Thanks for the tips.