TM4C1290NCPDT: Having problem reading I2C data.

I tried using Burst mode with the following results:

     while(I2CMasterBusy(I2C0_BASE)) {}                             // Wait if still running.
    I2CMasterSlaveAddrSet(I2C0_BASE, RtcAddr, I2CRead);            // This shifts the addr left 1.
    I2CMasterDataPut(I2C0_BASE, Register);                         //
    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);       // Send Register.
    while( ! I2CMasterBusy(I2C0_BASE)) {}                          // Wait for master to go busy,
    while(I2CMasterBusy(I2C0_BASE)) {}                             // then wait till done.
    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);       // Send Register.
    while( ! I2CMasterBusy(I2C0_BASE)) {}                          // Wait for master to go busy,
    while(I2CMasterBusy(I2C0_BASE)) {}                             // then wait till done.
    return(I2CMasterDataGet(I2C0_BASE));                           //

Here's the waveform:

I don't know where the 0x40 is coming from, the Register is #1.

Hi Charles,

The slave is a MAX31329 real time clock, and it seems to be reading things correctly as it will NAK an invalid register number and ACK valid ones.

I tried the ..BURST_SEND_START and then ...BURST_RECEIVE_FINISH but it didn't work.  I don't think Burst mode will work for this as whether the transaction is a Read or a Write is determined within the Address frame, so to do a write followed by a read won't I have to do a single write followed by a single read?

When I do a Single Send followed by a Single Receive (first code above) it does a Read followed by a a Read !! 

If I do a Burst Send Start followed by a Burst Receive Finish it does 2 Writes in a row of the same data.

If I do a Burst Send Start followed by a Single Receive it does a Receive followed by a Receive. (whew!)

Something funny is going on here.  Thanks, Doug

Reading section 3.2 of SLVA704 "Understanding the I2C Bus", it show that to be able to read a register the following has to happen:

How do I do this?

Thanks

Doug,

  Can you try like below code sequence. Does it make a difference? Note I did not include the I2CMasterBusy() and !I2CMasterBusy() as mentioned in the first reply. You still need them. 

    I2CMasterSlaveAddrSet(I2C0_BASE, RtcAddr, I2CWrite);      
    I2CMasterDataPut(I2C0_BASE, Register);                         
    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);  
    I2CMasterSlaveAddrSet(I2C0_BASE, RtcAddr, I2CRead);  
    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);   
    return(I2CMasterDataGet(I2C0_BASE));

Hi Doug,

  Glad your issue is resolved. Can you post your snippet of code so people in the community can benefit when using MAX31329 device. 

Very good.  I haven't implemented other than basics for the RTC.  I've also included the code I have so far for a backlight P/S chip LM3530UME-40.

//-- RTC I2C Register Address' and Bits --//

const u8 RtcStatusReg          = 0x00;

  const u8 RtcStatPsDectBit    = 0x80;

  const u8 RtcStatOsfBit       = 0x40;

  const u8 RtcStatPFailBit     = 0x20;

  const u8 RtcStatLosBit       = 0x10;

  const u8 RtcStatDifBit       = 0x08;

  const u8 RtcStatTifBit       = 0x04;

  const u8 RtcStatA2fBit       = 0x02;

  const u8 RtcStatA1fBit       = 0x01;

const u8 RtcIntEnReg           = 0x01;

  const u8 RtcIntEnDosfBit     = 0x40;

  const u8 RtcIntEnPFailBit    = 0x20;

  const u8 RtcIntEnDieBit      = 0x80;

  const u8 RtcIntEnTieBit      = 0x40;

  const u8 RtcIntEnA2ieBit     = 0x20;

  const u8 RtcIntEnA1ieBit     = 0x10;

const u8 RtcResetReg           = 0x02;

  const u8 RtcRstBit           = 0x01;

const u8 RtcCfg1Reg            = 0x03;

  const u8 RtcCfg1EnIoBit      = 0x08;

  const u8 RtcCfg1DataRetBit   = 0x04;

  const u8 RtcCfg1TimeoutBit   = 0x02;

  const u8 RtcCfg1EnOscBit     = 0x01;

const u8 RtcCfg2Reg            = 0x04;

  const u8 RtcCfg2ClkOutBit    = 0x80;

  const u8 RtcCfg2ClkOutHzBits = 0x60;    // 2 bits.

  const u8 RtcCfg2DipBit       = 0x08;

  const u8 RtcCfg2ClkInBit     = 0x04;

  const u8 RtcCfg2ClkInHzBits  = 0x03;    // 2 bits.

void RtcReset(void) {

    RtcWrite(RtcResetReg, RtcRstBit);

    RtcWrite(RtcResetReg, 0);

}

u8 RtcRead(u8 Register) {                                          //

    while(I2CMasterBusy(I2C0_BASE)) {}                             // Wait if still running.

    I2CMasterSlaveAddrSet(I2C0_BASE, RtcAddr, I2CWrite);           // Shifts addr left. Write Reg#.

    I2CMasterDataPut(I2C0_BASE, Register);                         //

    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);  // Send Register.

    while( ! I2CMasterBusy(I2C0_BASE)) {}                          // Wait for master to go busy,

    while(I2CMasterBusy(I2C0_BASE)) {}                             // then wait till done.

    I2CMasterSlaveAddrSet(I2C0_BASE, RtcAddr, I2CRead);            // Shifts addr left. Read Data.

    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE);    // Get Data.

    while( ! I2CMasterBusy(I2C0_BASE)) {}                          // Wait for master to go busy,

    while(I2CMasterBusy(I2C0_BASE)) {}                             // then wait till done.

    return((u8)I2CMasterDataGet(I2C0_BASE));                       //

}                                                                  //

void RtcWrite(u8 Register, u8 Data) {                              //

    while(I2CMasterBusy(I2C0_BASE)) {}                             // Wait if still running.

    I2CMasterSlaveAddrSet(I2C0_BASE, RtcAddr, I2CWrite);           // This shifts the addr left 1.

    I2CMasterDataPut(I2C0_BASE, Register);                         //

    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);  // Send Register.

    while( ! I2CMasterBusy(I2C0_BASE)) {}                          // Wait for master to go busy,

    while(I2CMasterBusy(I2C0_BASE)) {}                             // then wait till done.

    I2CMasterDataPut(I2C0_BASE, Data);                             //

    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH); // Send Data.

    while( ! I2CMasterBusy(I2C0_BASE)) {}                          // Wait for master to go busy,

}                                                                  // for back to back calls here.

Code for the LM3530UME-40 follows:

const   u8 BacklightAddr = 0x38;        // For LM3530UME-40

const u8 BL_GenRegAddr   = 0x10;

const u8 BL_GenI2CBit    = 0b00000001;

const u8 BL_GenMapBit    = 0b00000010;

const u8 BL_GenBriteBits = 0b00011100;

const u8 BL_Max5ma       = 0b00000000;

const u8 BL_Max8_5ma     = 0b00000100;

const u8 BL_Max12ma      = 0b00001000;

const u8 BL_Max15_5ma    = 0b00001100;

const u8 BL_BriteAddr    = 0xA0;

const u8 BL_BriteOff     = 0x00;

const u8 BL_Brite25Pct   = 0x20;

const u8 BL_Brite50Pct   = 0x40;

const u8 BL_Brite100Pct  = 0x7F;

void BacklightInit(void) {

    BacklightWrite(BL_GenRegAddr, BL_GenI2CBit |   // Simple I2C control.

                                  BL_GenMapBit |   // Linear Map.

                                  BL_Max12ma  );   // Max backlight current.

    BacklightWrite(BL_BriteAddr,  BL_BriteOff);    // Turn backlight off.

void BacklightLevel(u8 BriteVal) {

    if(BriteVal > BL_Brite100Pct) {

        Error(INVAL_BACKLIGHT_LEVEL);

    }

    BacklightWrite(BL_BriteAddr,  BriteVal);       // Set backlight level.

}

void BacklightWrite(u8 Register, u8 Data) {                        //

    while(I2CMasterBusBusy(I2C2_BASE)) {}                          // Wait if busy.

    I2CMasterSlaveAddrSet(I2C2_BASE, BacklightAddr, I2CWrite);     // This shifts the addr left 1.

    I2CMasterDataPut(I2C2_BASE, Register);                         //

    I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_SEND_START);  // Register.

    while( ! I2CMasterBusy(I2C2_BASE)) {}                          // Wait till busy.

    while(I2CMasterBusy(I2C2_BASE)) {}                             // Wait till done.

    I2CMasterDataPut(I2C2_BASE, Data);                             //

    I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH); // Data.

    while( ! I2CMasterBusy(I2C2_BASE)) {}                          // Wait till busy, for back to

}                                                                  // back calls here.

Note that needing the  while( ! I2CMasterBusy(I2C2_BASE)) {}  is probably because I'm only running the core clock at 20MHz.

Note also that I need to go back and implement calls to I2CMasterErr().

HI Doug,

 Thanks for sharing. I will bookmark this post for future reference.