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Setting GPIOCTL bits

David Pfaltzgraff
Expert 2475 points


I trying to use I2C2 on an LM4F231 using CCS5. I understand that the GPIOCTL bits in Port E to select the I2C peripheral. Is this something I must do explicity or is there a StellarisWare library routine that will help me?

I expect to see a call that involves GPIO_PE4_I2C2SCL and GPIO_PE5_I2C2SDA but haven't been able to find it. Also, supporting this is that GPIO_PCTL for port E is at zero after I set up the I2C hardware.

Thanks

  • 0
    Expert 2475 points

    It seems that I'm getting good at answering my own questions - or being able to ask questions with reasonably obvious answers!

    The function desired is GPIOPinConfigure() where the parameter is taken from the appropriate section of pin_map.h. This has the prequisite that "driverlib/pin_map.h" be included prior to the call.

  • 0
    TI__Expert 6140 points

    David,

     

    To enable the I2C peripheral you must first enable the port then configure the pins for their I2C function. This can all be done using StellarisWare calls:

     

    // GPIO port E needs to be enabled so these pins can be used.

    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);

     

    // Configure the pin muxing for I2C0 functions on port E4 and E5.

    GPIOPinConfigure(GPIO_PE4_I2C2SCL);

    GPIOPinConfigure(GPIO_PE5_I2C2SDA);

     

    Also make sure you include the correct headers to support the functions you would like to use:

    #include "driverlib/i2c.h"

    #include "driverlib/gpio.h"

     

     For more information please see the documentation included within StellarisWare. "<Your StellarisWare install directory>/docs". Also leveraging some existing examples can help as well.

  • 0 in reply to David Pfaltzgraff
    Guru 117855 points

    David Pfaltzgraff said:
    function desired is GPIOPinConfigure()

    You may wish to consider function GPIOPinType() as well.  These 2 functions are often bound together - more modern, high performance MCUs require such treatment...