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The mystery In the previous article, I briefly mentioned a slight difference between the ESP-Prog and the reproduced circuit, when it comes to EN: Focusing on EN, it looks like the voltage level goes back to 3.3V much faster on the ESP-Prog than on the breadboard circuit. The grid is horizontally spaced at 2ms, so … Continue reading Overanalyzing a minor quirk of Espressif’s reset circuit → The post Overanalyzing a minor quirk of Espressif’s reset circuit appeared first on Quentin Santos.
4 weeks ago

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More from Quentin Santos

Transistors in reverse and redundant circuits

The mystery In the previous article, I briefly mentioned a slight difference between the ESP-Prog and the reproduced circuit, when it comes to EN: Focusing on EN, it looks like the voltage level goes back to 3.3V much faster on the ESP-Prog than on the breadboard circuit. The grid is horizontally spaced at 2ms, so … Continue reading Transistors in reverse and redundant circuits → The post Transistors in reverse and redundant circuits appeared first on Quentin Santos.

4 weeks ago 15 votes
The missing part of Espressif’s reset circuit

In the previous article, we peeked at the reset circuit of ESP-Prog with an oscilloscope, and reproduced it with basic components. We observed that it did not behave quite as expected. In this article, we’ll look into the missing pieces. An incomplete circuit For a hint, we’ll first look a bit more closely at the … Continue reading The missing part of Espressif’s reset circuit → The post The missing part of Espressif’s reset circuit appeared first on Quentin Santos.

a month ago 122 votes
Reproducing Espressif’s reset circuit

I recently discussed how Espressif implements automatic reset, a feature that lets users easily update the code on an Espressif microcontroller. There are actually more subtleties than a quick look would suggest, and I spent a fair bit of time investigating them. This article and the next two present what I have learned. The current … Continue reading Reproducing Espressif’s reset circuit → The post Reproducing Espressif’s reset circuit appeared first on Quentin Santos.

a month ago 23 votes
The ESP32-S2 reset pin

RST defaults to high This is an addendum to the article about Espressif’s automatic reset. In that article, we observed the effect of the RST pin on the ESP32-S2-Saola-1RI board: I skipped over this topic quickly, so I am now taking the time to explain how the RST pin manages to have a defined behavior … Continue reading The ESP32-S2 reset pin → The post The ESP32-S2 reset pin appeared first on Quentin Santos.

2 months ago 29 votes

More in programming

Big O vs Hardware: Better Complexity ≠ Better Performance

Why Your O(log n) Algorithm Might Lose to O(n)

11 hours ago 4 votes
A Few Things About the Anchor Element’s href You Might Not Have Known

I’ve written previously about reloading a document using only HTML but that got me thinking: What are all the values you can put in an anchor tag’s href attribute? Well, I looked around. I found some things I already knew about, e.g. Link protocols like mailto:, tel:, sms: and javascript: which deal with specific ways of handling links. Protocol-relative links, e.g. href="//" Text fragments for linking to specific pieces of text on a page, e.g. href="#:~:text=foo" But I also found some things I didn’t know about (or only vaguely knew about) so I wrote them down in an attempt to remember them. href="#" Scrolls to the top of a document. I knew that. But I’m writing because #top will also scroll to the top if there isn’t another element with id="top" in the document. I didn’t know that. (Spec: “If decodedFragment is an ASCII case-insensitive match for the string top, then return the top of the document.”) href="" Reloads the current page, preserving the search string but removing the hash string (if present). URL href="" resolves to /path/ /path/ /path/#foo /path/ /path/?id=foo /path/?id=foo /path/?id=foo#bar /path/?id=foo href="." Reloads the current page, removing both the search and hash strings (if present). Note: If you’re using href="." as a link to the current page, ensure your URLs have a trailing slash or you may get surprising navigation behavior. The path is interpreted as a file, so "." resolves to the parent directory of the current location. URL href="." resolves to /path / /path#foo / /path?id=foo / /path/ /path/ /path/#foo /path/ /path/?id=foo /path/ /path/index.html /path/ href="?" Reloads the current page, removing both the search and hash strings (if present). However, it preserves the ? character. Note: Unlike href=".", trailing slashes don’t matter. The search parameters will be removed but the path will be preserved as-is. URL href="?" resolves to /path /path? /path#foo /path? /path?id=foo /path? /path?id=foo#bar /path? /index.html /index.html? href="data:" You can make links that navigate to data URLs. The super-readable version of this would be: <a href="data:text/plain,hello world"> View plain text data URL </a> But you probably want data: URLs to be encoded so you don’t get unexpected behavior, e.g. <a href="data:text/plain,hello%20world"> View plain text data URL </a> Go ahead and try it (FYI: may not work in your user agent). Here’s a plain-text file and an HTML file. href="video.mp4#t=10,20" Media fragments allow linking to specific parts of a media file, like audio or video. For example, video.mp4#t=10,20 links to a video. It starts play at 10 seconds, and stops it at 20 seconds. (Support is limited at the time of this writing.) See For Yourself I tested a lot of this stuff in the browser and via JS. I think I got all these right. Thanks to JavaScript’s URL constructor (and the ability to pass a base URL), I could programmatically explore how a lot of these href’s would resolve. Here’s a snippet of the test code I wrote. You can copy/paste this in your console and they should all pass 🤞 const assertions = [ // Preserves search string but strips hash // x -> { search: '?...', hash: '' } { href: '', location: '/path', resolves_to: '/path' }, { href: '', location: '/path/', resolves_to: '/path/' }, { href: '', location: '/path/#foo', resolves_to: '/path/' }, { href: '', location: '/path/?id=foo', resolves_to: '/path/?id=foo' }, { href: '', location: '/path/?id=foo#bar', resolves_to: '/path/?id=foo' }, // Strips search and hash strings // x -> { search: '', hash: '' } { href: '.', location: '/path', resolves_to: '/' }, { href: '.', location: `/path#foo`, resolves_to: `/` }, { href: '.', location: `/path?id=foo`, resolves_to: `/` }, { href: '.', location: `/path/`, resolves_to: `/path/` }, { href: '.', location: `/path/#foo`, resolves_to: `/path/` }, { href: '.', location: `/path/?id=foo`, resolves_to: `/path/` }, { href: '.', location: `/path/index.html`, resolves_to: `/path/` }, // Strips search parameters and hash string, // but preserves search delimeter (`?`) // x -> { search: '?', hash: '' } { href: '?', location: '/path', resolves_to: '/path?' }, { href: '?', location: '/path#foo', resolves_to: '/path?' }, { href: '?', location: '/path?id=foo', resolves_to: '/path?' }, { href: '?', location: '/path/', resolves_to: '/path/?' }, { href: '?', location: '/path/?id=foo#bar', resolves_to: '/path/?' }, { href: '?', location: '/index.html#foo', resolves_to: '/index.html?'} ]; const assertions_evaluated = assertions.map(({ href, location, resolves_to }) => { const domain = 'https://example.com'; const expected = new URL(href, domain + location).toString(); const received = new URL(domain + resolves_to).toString(); return { href, location, expected: expected.replace(domain, ''), received: received.replace(domain, ''), passed: expected === received }; }); console.table(assertions_evaluated); Email · Mastodon · Bluesky

10 hours ago 1 votes
Executives should be the least busy people

If your executive calendar is packed back to back, you have no room for fires, customers, or serendipities. You've traded all your availability for efficiency. That's a bad deal. Executives of old used to know this! That's what the long lunches, early escapes to the golf course, and reading the paper at work were all about. A great fictional example of this is Bert Cooper from Mad Men. He knew his value was largely in his network. He didn't have to grind every minute of every day to prove otherwise. His function was to leap into action when the critical occasion arose or decision needed to be made. But modern executives are so insecure about seeming busy 24/7 that they'll wreck their business trying to prove it. Trying to outwork everyone. Sacrificing themselves thin so they can run a squirrel-brain operation that's constantly chasing every nutty idea. Now someone is inevitably going to say "but what about Elon!!". He's actually a perfect illustration of doing this right, actually. Even if he works 100-hour weeks, he's the CEO of 3 companies, has a Diablo VI addiction, and keeps a busy tweeting schedule too. In all of that, I'd be surprised if there was more than 20-30h per company per week on average. And your boss is not Elon. Wide open calendars should not be seen as lazy, but as intentional availability. It's time we brought them back into vogue.

4 days ago 6 votes
Dispatch 012: Local-first talks, Automerge 3, and Scribbling on a Google Calendar

A secret master plan, the official launch of Automerge 3, and an update on Sketchy Calendars

4 days ago 7 votes
React Server Components with Vite and React-Router (tip)

Create a small example app and send payloads from the server to the client using RSC's

5 days ago 11 votes