I2C Nothing

I feel your pain!  I've spent the better part of 2 days getting my own I2C code working on the F28335 (and I spent a good 2 days getting a project to successfully merge SYS-BIOS hello world example to play nice with all the experimenter board peripheral libraries of the I2C EEPROM example, but that's another story).

As for documentation of I2C for C2000, it takes a bit of looking.  First, I started out with the manual for my chip:

http://www.ti.com/lit/ds/sprs439m/sprs439m.pdf

Unfortunately, they seemed to have forgotten to list the peripherals manual on the F28335 webpage in the listing of documents.  That was a bit tricky to find:

http://www.ti.com/lit/ug/spru566j/spru566j.pdf

On page 14 section 3.10 of the 28x DSP Peripherals manual, it will refer you to even more specific I2C manuals.  In my case:

http://www.ti.com/lit/ug/sprug03b/sprug03b.pdf

This 3rd manual goes into the detail you need to cover all the registers and how to setup them up.  Well....except it glosses over FIFO as you said.  But it turns out the EEPROM example uses FIFO if you look carefully at it.  It's really not too hard.  You set the counter register I2CCNT to the byte count you have (with a maximum of up to 16 bytes at a time), then load your data into I2CDXR one byte at a time, and finally trigger a transmit with I2CMDR.

I had the issue of seeing just the start condition at first and no data sent.  I can't quite backtrace my debuggins, but I think my MDR settings before and after weren't quite right.

Here's the bulk of my code to do a successful I2C write to a 4-digit 7-segment LED driver to test the LEDs being lit.

void I2CA_Init(void);

//
// RAM Function references
// These are defined by the linker (see F28335.cmd)
//
extern Uint16 RamfuncsLoadStart;
extern Uint16 RamfuncsLoadEnd;
extern Uint16 RamfuncsRunStart;



/*
 *  ======== main ========
 */
Void main()
{

    MemCopy(&RamfuncsLoadStart, &RamfuncsLoadEnd, &RamfuncsRunStart);  // needed if you use the DELAY_US, especially ADC setup


    // Step 1. Initialize System Control:
    // PLL, WatchDog, enable Peripheral Clocks
    // This example function is found in the DSP2833x_SysCtrl.c file.
    InitSysCtrl();


    // Step 2. Initalize GPIO:
    // This example function is found in the DSP2833x_Gpio.c file and
    // illustrates how to set the GPIO to it's default state.
    // InitGpio();
    // Setup only the GP I/O only for I2C functionality
    InitI2CGpio();



    // Step 4. Initialize all the Device Peripherals:
    // This function is found in DSP2833x_InitPeripherals.c
    // InitPeripherals(); // Not required for this example
    I2CA_Init();


    DELAY_US(1000000);


    // Check for stop condition
    while (I2caRegs.I2CMDR.bit.STP == 1)
    {
        uiTemp = 1;
    }


    I2caRegs.I2CSAR = 0x38;

    // Check if bus busy
    while (I2caRegs.I2CSTR.bit.BB == 1)
    {
        uiTemp = 1;
    }



    I2caRegs.I2CCNT = 6;

    I2caRegs.I2CDXR = 0x00;
    I2caRegs.I2CDXR = 0x7F;
    I2caRegs.I2CDXR = 0xFF;
    I2caRegs.I2CDXR = 0xFF;
    I2caRegs.I2CDXR = 0xFF;
    I2caRegs.I2CDXR = 0xFF;


    //  Engage FIFO transmit
    I2caRegs.I2CMDR.all = 0x6E20;

    //  Infinite loop to catch after successful transmit
    while (1)
    {
        uiTemp = 1;
    }

} // end main

void I2CA_Init(void)
{
   // Initialize I2C
   I2caRegs.I2CSAR = 0x3C;            // Slave address of first I2C 4-digit display controller

   #if (CPU_FRQ_150MHZ)             // Default - For 150MHz SYSCLKOUT
     I2caRegs.I2CPSC.all = 14;       // Prescaler - need 7-12 Mhz on module clk (150/15 = 10MHz)
   #endif
   #if (CPU_FRQ_100MHZ)             // For 100 MHz SYSCLKOUT
     I2caRegs.I2CPSC.all = 9;        // Prescaler - need 7-12 Mhz on module clk (100/10 = 10MHz)
   #endif

   I2caRegs.I2CCLKL = 76;            // NOTE: must be non zero
   I2caRegs.I2CCLKH = 38;            // NOTE: must be non zero
   I2caRegs.I2CIER.all = 0x0;        // Disable interrupts



   I2caRegs.I2CMDR.all = 0x0020;    // Take I2C out of reset
                                       // Stop I2C when suspended



   I2caRegs.I2CFFTX.all = 0x6000;    // Enable FIFO mode and TXFIFO
   I2caRegs.I2CFFRX.all = 0x2040;    // Enable RXFIFO, clear RXFFINT,

   return;
}

The above settings for CCLKL and CCLKH will get a 86 kHz SCL rate for the I2C and the predivisor gets you 10 MHz (150 MHz system / (14+1) ) for the I2C module clock.

I will probably start a separate thread if this isn't acknowledged, as it needs to be fixed.  On page 34 section 5.7.1 of TMS320x280x Inter-Integrated Circuit Module, the formula is WRONG!  If you refer to the flowchart on page 14, it is clear that the prescaler gets you the I2C clock frequency.  So the denominator in that equation is the system clock (150 MHz in my case) NOT the I2C clock.  The prescaler is already in that equation!   

UPDATE/EDIT: See Trey's post below.  I was confused thinking the equation referred to the I2C module clock.  It refers to the I2C input clock, which is the SYSCLK.

That means that the controlSUITE EEPROM I2C example probably has an unintended clock rate 15 X higher than it should be, it's well over 100 kHz.

Now a read might be a bit trickier to do.

Hope that helps.

I'm in a bit of a hurry, so I didn't get to look to closely at your code.