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trouble toggling GP[35] on DM6435

Eric Bryan
Expert 1045 points

There must be a config option or limitation I have overlooked.  I can't get GP[35] to change output status from low to high.  I have the following settings for configuration:

CFG_PINMUX0= 0x50A00000;

CFG_PINMUX1= 0x00604510;

CFG_VDD3P3V_PWDN = 0x00000000;

VPFE_CCDC_SYN_MODE =      0x00030400; (I've tried not init'ing any of the VPFE as well...)

GPIO_DIR23_IO_VALUE  = 0x0370fff0u;

AEM and AEAW are both zero (all pins tied low)

I can toggle GP[33] in the same bank.  GP[34] is not used and GP[36] is used for the CCD0 data bit.

What am I overlooking?

 

Eric Bryan

 

  • 0
    TI__Guru*** 125430 points

    I double checked all your pinmux settings and they're correct.  Is it a coding error such as an incorrectly defined register location or lack of using volatile keyword?  Is it a board issue such as that pin shorted to ground?

  • 0 in reply to Brad Griffis
    Expert 1045 points

    This pin drives the base of a transistor thru a series resistor.   I had already pulled that series resistor.  No joy. 

    I call a function to set/clear the pin.  For GP[33] and multiple others it works fine. 

    With the series resistor pulled, I applied a 4.7K pu to the line.  GP[35] is going high when the pu is applied.  It is behaving like it is an input.  Setting the GP[35] high or low does not change the voltage level when the pu is applied.  Any settings we've missed that could do this?

    Series resistor was a 2.2K into the base of a '2222 transistor with emitter grounded.  This isn't a high load (about 1.3mA) but could the output driver be damaged?  I've tried two of our boards during testing and this output does not work on either of them.

  • 0 in reply to Eric Bryan
    Expert 1045 points

    Problem found....

    CFG_PINMUX0= 0x50A00000;

    should be:

    CFG_PINMUX0= 0x50500000;

    I skipped the reserved bit at 27.

     

     

     

  • 0 in reply to Eric Bryan
    TI__Guru*** 125430 points

    Ah ha!  Secret bit!  I didn't check that one -- good find and thanks for reporting back.