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What is the purpose of Debounce Functional clock on AM335x processor? In the technical reference they say: "The de-bounce clock is used for the de-bouncing cells". What cells? I am little confused with this.

Technical reference http://www.ti.com/lit/pdf/spruh73 page 4868

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  • \$\begingroup\$ How about providing a link to the technical reference and a page number? \$\endgroup\$
    – Tut
    Jun 22, 2015 at 13:44
  • \$\begingroup\$ I provided, look now. :) \$\endgroup\$
    – user76920
    Jun 22, 2015 at 13:47
  • \$\begingroup\$ Hi, I would recommend you check out TI forums, they got employees paid to answer such question \$\endgroup\$
    – MathieuL
    Jun 25, 2015 at 12:35
  • \$\begingroup\$ Are you familiar with the term "debouncing", if not read this: web.engr.oregonstate.edu/~traylor/ece473/lectures/debounce.pdf It looks to me as if the AM335x has debouncing circuits built-in and these need a clock, this clock is called de-bounce clock. This is just me guessing so correct me please if I misunderstood. \$\endgroup\$ Jun 25, 2015 at 13:02
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    \$\begingroup\$ Actually, I got a lot of feedback from their forum for 1 of my student project. MultiNationals don't use Forums, they can use a direct line of support. \$\endgroup\$
    – MathieuL
    Jun 25, 2015 at 13:35

1 Answer 1

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When it says "cells" it's simply referring to the I/O logic cells that are a part of the GPIO module. As stated in the reference (25.2.2) the GPIO modules require two clocks: the interface clock and the debounce clock.

If you go further down to section 25.3.2.1 it describes the debounce clock: "The debouncing clock is used for the debouncing sub-module logic (without the corresponding configuration registers). This module can sample the input line and filters the input level using a programmed delay." So, it does what you'd think (as the name describes), it filters out any glitches/false positives on a GPIO that's been assigned as an input.

Go a little further and in section 25.3.4.4 it describes the debouncing time and how to calculate it and enable it on a general purpose input.

And finally I found this https://e2e.ti.com/support/arm/sitara_arm/f/791/t/217327 where someone is talking about using the debounce feature.

Hope that helps clear up the mud some.

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