LPC824 IIC的问题

coolhe88

您好！关于LPC824M201的IIC，有个问题请教一下，谢谢！
硬件：I2C主机：LPC824M201，内部晶体；IIC从机：APDS-9960；IIC两线上拉10K电阻
工具：J-Link V9
问题：在线仿真，主机可以读到从机，功能正常；下载后重新上电，主机识别不了从机。

IIC初始化代码：
//************************************************************//
void I2C_Init(void)
{

  LPC_SYSCON->SYSAHBCLKCTRL |= (I2C0 | SWM);  // Enable clocks to I2C0, SWM (see lpc8xx_syscon.h)

  LPC_SWM->PINENABLE0 &= ~(I2C0_SCL|I2C0_SDA); // Use for LPC824(Enable I2C on P0_10 and P0_11)

  // Give I2C0 a reset  (see lpc8xx_syscon.h)
  LPC_SYSCON->PRESETCTRL &= (I2C0_RST_N);  //Reset IIC.
  LPC_SYSCON->PRESETCTRL |= ~(I2C0_RST_N);  //Clear IIC reset.

  // Configure the I2C0 clock divider
  // Desired bit rate = Fscl = 100,000 Hz (1/Fscl = 10 us, 5 us low and 5 us high)
  // Use default clock high and clock low times (= 2 clocks each)
  // So 4 I2C_PCLKs = 100,000/second, or 1 I2C_PCLK = 400,000/second
  // I2C_PCLK = SystemClock = 30,000,000/second, so we divide by 30/.4 = 75
  // Remember, value written to DIV divides by value+1
  LPC_I2C0->DIV = (75 - 1);

  LPC_I2C0->CFG = CFG_MSTENA;   //Enable LPC824 as IIC master.
}

//************************************************************//
从机检测代码：
//************************************************************//
unsigned char Slave_Check(void)
{
        unsigned char uTemp=0;
        WaitI2CMasterState(LPC_I2C0, I2C_STAT_MSTST_IDLE); // Wait the master state to be idle
        LPC_I2C0->MSTDAT = (Slave_address<<1) | 0;    // Address with 0 for RWn bit (WRITE)
        LPC_I2C0->MSTCTL = CTL_MSTSTART|CTL_MSTCONTINUE;                   // Start the transaction by setting the MSTSTART bit to 1 in the Master control register.
        WaitI2CMasterState(LPC_I2C0, I2C_STAT_MSTST_MTR);   // Wait for the address to be ACK'd

        LPC_I2C0->MSTDAT = APDS9960_ID;                           // Send the data to the slave
        LPC_I2C0->MSTCTL = CTL_MSTCONTINUE;                // Continue the transaction
        WaitI2CMasterState(LPC_I2C0, I2C_STAT_MSTST_MTR);   // Wait for the data to be ACK'd

        LPC_I2C0->MSTDAT = (Slave_address<<1) | 1;    // Address with 1 for RWn bit (Read)
        LPC_I2C0->MSTCTL = CTL_MSTSTART;                   // Start the transaction by setting the MSTSTART bit to 1 in the Master control register.
        WaitI2CMasterState(LPC_I2C0, I2C_STAT_MSTST_MRR);   // Wait for the address to be ACK'd

        uTemp=LPC_I2C0->MSTDAT;
        LPC_I2C0->MSTCTL = CTL_MSTSTOP;                    // Send a stop to end the transaction
        if(uTemp==0xAB)
        {
                return True;
        }
        else
        {
        
        return False;
        }
}

//************************************************************//

我知道答案 目前已有2人回答

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Splore.Liu

抓IIC波形看吧，示波器/逻辑分析仪都行。
感觉系统时钟异常。

小恩GG

正如二楼说的，抓取波形看看，比较一下仿真和实际代码运行时的差别