Timeline for Are pull-up resistors needed when connecting buttons to a IO expander?
Current License: CC BY-SA 3.0
14 events
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| Apr 13, 2017 at 12:25 | history | edited | Enric Blanco |
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| Apr 4, 2017 at 23:26 | comment | added | jonk | @Basj Yeah. I'd probably try that out and see how it goes, anyway. It's probably fine. (If this were for someone where I cared about something robust, I'd add a lot more. Switches cost too much these days not to add some circuitry to them, both for analog low pass and/or debouncing as well as stronger ESD protection. And I'd probably not use a boutique part like that. Plus, I've got buckets of 40 cent micros and I'd use one of those, instead. I can control the responsiveness, to my liking, that way. Lots less space, too. | |
| Apr 4, 2017 at 20:04 | comment | added | Basj | Thanks @jonk for your advice. I added a schematic, showing what I want to achieve: connecting multiple switches to Raspberry Pi. In this context, do you think all is ok, without stronger pull-up resistors? | |
| Apr 4, 2017 at 12:08 | history | edited | Basj | CC BY-SA 3.0 |
added schematic
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| S Apr 4, 2017 at 10:31 | history | suggested | Enric Blanco | CC BY-SA 3.0 |
Typo corrected ("registers" instead of "resistors") + clarification added ("external") + tag added (expander)
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| Apr 4, 2017 at 10:30 | review | Suggested edits | |||
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| Apr 4, 2017 at 9:43 | history | edited | Basj | CC BY-SA 3.0 |
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| Apr 4, 2017 at 9:38 | answer | added | Enric Blanco | timeline score: 5 | |
| Apr 4, 2017 at 9:37 | history | edited | Basj | CC BY-SA 3.0 |
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| Apr 4, 2017 at 9:33 | review | Close votes | |||
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| Apr 4, 2017 at 9:21 | comment | added | jonk | Datasheet says that it supplies at least 40 \$\mu\$A, which is far more than the maximum leakage of an input and enough to pull it into a known state if there aren't other paths from dirt, human skin oils, and the like. It's weak, though. There is also ESD protection on each pin in the device. So if all that meets your needs, fine. If not, you can provide additional protection and/or a stronger pull-up. You don't disclose the environment, so others can only guess what's best for your case. | |
| Apr 4, 2017 at 9:16 | history | edited | Marcus Müller |
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| Apr 4, 2017 at 9:15 | comment | added | Marcus Müller | "some place on the internet" vs "the official datasheet". Guess who's right. Anyway, without a schematic of what you want to build, this question remains unclear. | |
| Apr 4, 2017 at 9:00 | history | asked | Basj | CC BY-SA 3.0 |