About processing of debug pins (SWDCK, SWDIO)

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noha_3407421
Level 3
Level 3
Distributor - TED (Japan)
First like received 10 replies posted 10 questions asked

Hello,

I inquired about the SWD pin in the following community.

    https://community.cypress.com/message/164808#164808

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

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1 Solution
Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

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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2 Replies
Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

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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Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

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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