• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 82 subscribers
  • Views 1479 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

strange behaviour on GPIOs

Valdis Ivanov
Prodigy 140 points
Other Parts Discussed in Thread: TMS320F28027

Hi all !

I am working with TMS320F28027 .  I have detected a strange behaviour on GPIO2, GPIO3, GPIO4, GPIO5 at conecting to my target. I use this outputs for alternative functions ePWM2A, ePWM2B  ePWM3A, ePWM3B respectively.  Them pull up function is disabled by default (see page 95 System control and reset). But when I connect to my target via XDS100 emulator, I see PWM impulses on this outputs, frequency of this impulses is 60 kHz. I used this value for setting my ePWM2 and ePWM3 in my code.   It seems to start execute code and GPIOs behave as they are commanded by my code. But I have not run my code in debugger.

How do I solve this problem? Thanks in advance!

  • 0
    Prodigy 140 points

    Hi all !

    Why GPIO2...GPIO5 are driven high during connecting to my target, if them pull up function disabled by default ?

    Thanks in advance!

  • 0 in reply to Valdis Ivanov
    Expert 2355 points

    I have a feeling what is happening here.  When you are not connected to your target (i.e. not in debug mode), you have zero control over what the chip is doing.  Basically it is free running with whatever code it has on there.  This may be code in RAM from the last time you entered debug mode and you havent removed power since or it may be some code in Flash.

    Here are some ways to see if this is the problem (i.e. how to make it go away):

    1) Connect to the target but do not run your code.  The GPIOs should not be driven at all as you would expect.

    2) Erase the flash, turn off the power to the board, wait a bit and then start again.  The GPIOs should not be behaving strangely anymore. 


    Hopefully this helps,

     

    Tim