About processing of debug pins (SWDCK, SWDIO)

harukawa.nr_3407421 Aug 9, 2018 1:58 AM

Hello,

I inquired about the SWD pin in the following community.

This is another inquiry about SWD pin processing.

Q1.

Is it OK to keep the SWD pin open?

Q2.

Does the SWD pin have an internal pull-up like the XRES pin?

Best regards,

Harukawa

1. Re: About processing of debug pins (SWDCK, SWDIO)

user_1377889 Aug 9, 2018 4:19 AM (in response to harukawa.nr_3407421)

When you do not use the SWD and SDA pins for debugging (having set them to GPIO) they act just like "normal" IO pins. You may (and may not) configure them having internal pullups and other drive modes as shown in the pin's datasheet. When set to GPIO you still can use the pins for programming the device using a programmer.

Bob
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2. Re: About processing of debug pins (SWDCK, SWDIO)

VasanthR_91 Aug 10, 2018 5:26 AM (in response to harukawa.nr_3407421)

Hi Noritomo san,

Q1.
Is it OK to keep the SWD pin open?

Are you asking in cases when SWD is not being used? In that case they act like regular IO pins. . Normally it suggested to keep the unused pins in HighZ mode( which is by default).

Q2.
Does the SWD pin have an internal pull-up like the XRES pin?
The SWDIO have internal pull-up and SWDCK will be have an internal pull-down normally when SWD is enabled.

Best Regards,
VRS
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