TMS320F280049C: Unwanted pulse on GPIO during Power On/OFF

[neeteen09]

Hello,

I'm using TMS320F280049C micro-controller (Texas).

While testing its GPIO behavior during power on/off, I found a high to low transition on GPIO pin ,on every power on/off

I'm checking the waveform on GPIO pin of micro-controller itself.

I have used the same code provided by texas for GPIO initialization (C2000 examples)

//Initialization code as follows:-

GpioCtrlRegs.GPAPUD.bit.GPIO3 = 0; //Enable pull-up on GPIO3

GpioDataRegs.GPASET.bit.GPIO3 = 1; //Load output Latch

GpioCtrlRegs.GPAMUX1.bit.GPIO3 = 0; //GPIO3= GPIO3

GpioCtrlRegs.GPADIR.bit.GPIO3 = 1; //GPIO3=output

Attatchment:- Waveform during Power On/off.

 

[barry]

What you're seeing is perhaps due to the output going tri-state. Do you see this behavior on every pin? If not, what is different about what is connected to this pin? Is there a capacitance? Maybe you need a pull-down resistor on the pin.

 

[KlausST]

Hi,

What is connected to the pin?

As a general recommendation: don't leave it floating. You can't expect any level from a floating signal, because it is not defined.
And, because a floating signal is high impedance it can be influenced from any signal nearby.

Maybe you just see coupling effects from another signal.

Klaus