TM4C123GE6PM: TM4C123 changing the clock speed to 100 KHz

shai kon

Expert 1960 points

Part Number: TM4C123GE6PM

Hello,

I'm using this function to initialize the 2nd I2C module on my TM4C123 :

I2CMInit(&g_sI2CInst, I2C2_BASE, INT_I2C2, 0xFF, 0xFF, SysCtlClockGet());

This gives me an SCL with a frequency of 400 KHz.

How can I change it to 100 KHz ?

over 6 years ago

0 Bob Crosby over 6 years ago

TI__Guru 72500 points

To run at 100KHz, replace the I2CMInit function with your own copy and change the last argument in the function MAP_I2CMasterInitExpClk to "false".

void
I2CMInit(tI2CMInstance *psInst, uint32_t ui32Base, uint_fast8_t ui8Int,
         uint_fast8_t ui8TxDMA, uint_fast8_t ui8RxDMA, uint32_t ui32Clock)
{
    //
    // Check the arguments.
    //
    ASSERT(psInst);
    ASSERT((ui32Base == I2C0_BASE) || (ui32Base == I2C1_BASE) ||
           (ui32Base == I2C2_BASE) || (ui32Base == I2C3_BASE) ||
           (ui32Base == I2C4_BASE) || (ui32Base == I2C5_BASE) ||
           (ui32Base == I2C6_BASE) || (ui32Base == I2C7_BASE) ||
           (ui32Base == I2C8_BASE) || (ui32Base == I2C9_BASE));
    ASSERT(ui8Int);
    ASSERT(ui32Clock);

    //
    // Initialize the state structure.
    //
    psInst->ui32Base = ui32Base;
    psInst->ui8Int = ui8Int;
    psInst->ui8TxDMA = ui8TxDMA;
    psInst->ui8RxDMA = ui8RxDMA;
    psInst->ui8State = STATE_IDLE;
    psInst->ui8ReadPtr = 0;
    psInst->ui8WritePtr = 0;

    //
    // Initialize the I2C master module.
    //
    MAP_I2CMasterInitExpClk(ui32Base, ui32Clock, false);

    //
    // Enable the I2C interrupt.
    //
    MAP_IntEnable(ui8Int);
    MAP_I2CMasterIntEnableEx(ui32Base, I2C_MASTER_INT_DATA);
}

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TM4C123GE6PM: TM4C123 changing the clock speed to 100 KHz