TMS320F28035 PMBus Module: I2caRegs.I2CSTR.bit.SDIR Problem

user4227283

Hello,

I use PMBus Demo in order to form a larger program. The larger program has a ePWM interrupt and do main process in it. When ePWM interrupt not come, PMBus works, and ePWM interrupt comes, it stoppes.

The Demo itself runs rightly. But in my program when I send Read/Write commands, such as ON_OFF_CONFIG, it returns NACK.

I checked the program and registers and found the problem. when the program runs to 'if (I2caRegs.I2CSTR.bit.SDIR == 0)', neither read commands nor write commands, the SDIR is 0. After a little time SDIR changes to right value. The part of the program is shown below.

case RWBYTE: //read/write byte
        while(!I2caRegs.I2CSTR.bit.AAS); //wait until addressed by master
        if (I2caRegs.I2CSTR.bit.SDIR == 0) //determine if slave should send/receive
       { //slave receiver
              while(!I2caRegs.I2CSTR.bit.RRDY);    //wait for the data
             PMBusSlave_ReceiveBuffer[0] = I2caRegs.I2CDRR; //get the received data
              StopCpuTimer0();    //No timeout, so stop the timer
             ReloadCpuTimer0();    //Reload the period value (35 ms timeout)
        }
        else
        { //slave transmitter
             while(!I2caRegs.I2CSTR.bit.XRDY);    //make sure I2CDXR is clear
            I2caRegs.I2CDXR = PMBusSlave_TransmitBuffer[0]; //send the data
             StopCpuTimer0();    //No timeout, so stop the timer
             ReloadCpuTimer0();    //Reload the period value (35 ms timeout)
        }
        break;