TMS320F28335: GPIO status during power on reset

Green,

is there any external circuitry attached to GPIO 58?

What is "D301", I am not familiar with this device?

It looks like GPIO58 might be entering a high-z state, during the time you have marked as "Reset" you can see that it isn't strongly pulled to 3.3 V or 0 V.

Regards,
Cody 

Green,

one more question, can you confirm that the Pink signal is XRSn?

Thanks,
Cody

Hi Cody:

Customer feedback：

1, Gpio58 is used as the output and the external circuit is connected to the optocoupler chip.

2, D301 is a power reset chip.

3, Pink signal confirmed to be XRSn.

During reset, gpio58 level is only about 2.4V before low level pulse. If the gpio58 is pulled up externally, the reset period can reach 3.3V, but the low-level pulse still appears at the end of the reset. Not only this pin, but other pins are the same.

Best regards

Understood. Thank you for the feedback.

Please provide a picture of VDDIO, VDD, GPIO58, and XRSn at the same time.

There are some power sequencing requirements and we need to check if those are correct.

Regards,
Cody 

Hi Cody:

This is the schematic：

This is the Sequence diagram：

My customer hasn't provided the VDDIO and VDD Sequence diagram, and he thinks that this kind of situation is easy to occur when the control board is power on or off quickly

I hope the above pictures can help.

Best regards

Green,

the schematic looks OK to me.

We need to see the power rails when this conditions occurs. There are power sequencing requirements which could be causing this issue.

Regards,
Cody 

Hi Cody:

Thank you for your reply, I'll ask my customer to followup this post.