Serial wire debug pin is pulled down/up internally.

jun1 — Tue, 04 Dec 2018 03:03:49 GMT

Please kindly advise.

I have a question about SWD hardware.

In the manual "Document Number: MKMxxZxxACxx5RM Rev. 1, 09/2014"
"9.2 Debug Port Pin Descriptions" has the following description.

Serial Wire Clock. This pin is the clock for debug logic when in Serial Wire Debug mode. This pin is pulled down internally.
Serial wire debug data input / output. The SWD_IO pin is used by an external debug tool for communication and device control.

There are SWD_CLK pull-down and SWD_IO pull-up.
I have a question about this.
① What is the value of this pull-up resistor and pull-down resistor?
② Does it not have to pull up pulled down externally?
Or should I do it?
③ If the pull-up / pull-down is required, how much resistance?

I do not have good English.

Thank you.

Re: Serial wire debug pin is pulled down/up internally.

Robin_Shen — Tue, 04 Dec 2018 08:51:31 GMT

① internal 30 kΩ to 60 kΩ
② It does not have to pull up pulled down externally. But external pull resistors are recommended.
③ external 4.7 kΩ to 10 kΩ

Best Regards,

Robin

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Serial wire debug pin is pulled down/up internally.

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