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F28335 GPIO0-GPIO11 pins

Alex Oren
Intellectual 480 points
Other Parts Discussed in Thread: CONTROLSUITE

Hi,

I'm using the TMS320C2000 experimental kit.

After entering Debug mode with any code (different labs or available examples) I'm observing GPIO0-GPIO11 pins.

According to the datasheet the pullups on GPIO0–GPIO11 pins are not enabled at reset.

Each time I'm pressing F5 for the next software step these pins changes their state randomly - with no connections to the code.

Physically these pins are not connected. After adding 20-30k pull down resistors these pins are at stable low but I also can't make it high using e.g GpioDataRegs.GPASET.bit.GPIO4 = 1;

All other ping 12... are always high and respond as expected to when trying to toggle them.

Is it normal? are these pins floating?

What should I do if i want to use a GPIO that will be always low at reset?

Thank

  • 0
    Guru 192875 points
    Hi Alex,

    You can configure GPAPUD to enable internal pull-up. Also, whatever you're observing is False as GPIOs 0-11 are pulled-down after reset and not left floating. Check the GPADAT register for the pins during the debug session for their status.

    Regards,
    Gautam
  • 0 in reply to Gautam Iyer
    Intellectual 480 points

    Hi Gautam,

    Thanks for your answer.

    The first picture that I see after clicking the debug button is attached

    Why GPIO0-GPIO11 are not all equal to 0?

    After exiting the debug mode and entering again the picture is as follows:

    The situation is different  - why?

    This is even before I started configuring something.

    Is it a common practice to add an external  pull downs?

    All other pins 12-87 are high - due to internal pull ups.

    Thanks

  • 0 in reply to Alex Oren
    Guru 192875 points

    That's Strange Alex! I would suggest you to try with some sample code esp. some communication example which does not use GPIO0 to GPIO11.
    C:\ti\controlSUITE\device_support\f2833x\v141\DSP2833x_examples_ccsv5\sci_echoback

    Also, check the GPIO configuration file for any pre-configurations.