ePWM Pins jumping to HIGH while flashing the program

Prakash Kumar Thulasi Kumar

Expert 2015 points

Other Parts Discussed in Thread: TMS320F28027

Hi Guys,

TMS320F28027

All the internal pull up resistors of ePWM pins are disabled by default. But while flashing the program, the ePWM pins are jumping(high and low). This causes the gate drives to turn ON which will be a problem in live net conditions. Is there any way to avoid this from happening?

What is the case for GPIO (pull ups are enabled by default)?? Will it jump like this during flashing??

Thanks in advance.

over 9 years ago

0 Gautam Iyer over 9 years ago

Guru 192875 points

Hi Prakash,

Prakash Kumar Thulasi Kumar said:
This causes the gate drives to turn ON which will be a problem in live net conditions. Is there any way to avoid this from happening?

Your power section should always be off during flashing the mcu.

Prakash Kumar Thulasi Kumar said:
What is the case for GPIO (pull ups are enabled by default)?? Will it jump like this during flashing??

Check this post from Willaim:

Regards,

Gautam

0 Prakash Kumar Thulasi Kumar over 9 years ago in reply to Gautam Iyer

Expert 2015 points

Thanks Gautam.
Any idea on how long the GPIO is high during flashing?

0 Gautam Iyer over 9 years ago in reply to Prakash Kumar Thulasi Kumar

Guru 192875 points

No I'm not sure but this happens during flashing! I would guess until the completion of erase process.

0 Manish Bhardwaj over 9 years ago in reply to Gautam Iyer

TI__Mastermind 43730 points

Do you have any pull down resistor connected between the PWM pin and the Gate driver input?

As the Gate Driver input model is unknown and by default the PWM pin after reset is configured as input, albeit the PWM pin pull up is disabled by default, it is not a good state to be in.

If you can comment on the above question it will help us understand your issue.

We typically use 10K Res pull down quite commonly on our power designs.

0 Prakash Kumar Thulasi Kumar over 9 years ago in reply to Manish Bhardwaj

Expert 2015 points

Hi Manish,

Gautam is talking about the GPIO. In TMS320F28027, the Pull ups of GPIO s are enabled by default. So they remain HIGH until the completion of erase process as said by Gautam.

And my design has a 10K pull down resistor between PWM OUT and Gate driver IN. But I still experience floating issues during flashing.

0 Prakash Kumar Thulasi Kumar over 9 years ago

Expert 2015 points

Using an AND gate with all those outputs seems to be a better solution, provided one of the AND Gate's input is triggered externally.

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ePWM Pins jumping to HIGH while flashing the program