ADC external interrupt polarity

mario mezzarobba

Other Parts Discussed in Thread: TMS320F28335

Hi,

I am working with a TMS320F28335 bord, I am doing some aquisitions with the adc module, triggering them by an external interrupt at GPIO17. Till then its works just fine, I obtain the measures and all; the problem is that I want to trigger the aquisition with the falling edge of the triggering signal, but even by setting (in an EALLOW environment):

    GpioCtrlRegs.GPADIR.bit.GPIO17=0; //gpio17 is an input
   GpioCtrlRegs.GPAPUD.bit.GPIO17=0;

   GpioIntRegs.GPIOXINT2SEL.bit.GPIOSEL=17;//17
   GpioCtrlRegs.GPAQSEL2.bit.GPIO17=2;

   XIntruptRegs.XINT2CR.bit.ENABLE=1;
   XIntruptRegs.XINT2CR.bit.POLARITY=0;//falling edge

its still aquire in the raising edge.

Thank in advance,

Mario.

over 11 years ago

0 Bill Finger over 11 years ago

Genius 3735 points

Mario,

To quote from sprufb0d, page 101:

"To use XINT2 as ADC start of conversion, enable it in the ADCTRL2 register. The ADCSOC
signal is always rising edge sensitive."

What I would do is trigger an GPIO interrupt by falling edge, and inside there trigger the ADC by software. Or put an inverter in your circuit.

Regards,

Bill

0 mario mezzarobba over 11 years ago in reply to Bill Finger

Prodigy 20 points

Thank you Bill,

some how I missed that "The ADCSOC signal is always rising edge sensitive."

Regards.

Mario

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ADC external interrupt polarity