Top all-time · #4164
Matthew Petroff
Personal blog · mpetroff.net · on HN as mpetroffsciencehardwaredesign
Matthew Petroff's personal blog at mpetroff.net covers science, hardware and design. Since 2012, 19 different Hacker News readers have linked it 27 times, most often “New Amazon Dash Button Teardown (JK29LP)”. It is still writing: the last post was on 2025-06-29, and you can follow it by feed.
Too few sampled comments (13) to say how often HN recommends it.?
Why HN links it
HN readers link Matthew Petroff's posts on Amazon Dash button teardowns, a Kindle e-ink weather display, and pre-calculated Knuth-Plass line breaks for web pages. Commenters cite them as sources.
Summarised by Claude from a sample of 13 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
A postdoc in cosmology at CfA, Matthew Petroff's interests include photography, cartography, embedded electronics design, and robotics.
Most-linked posts?
- New Amazon Dash Button Teardown (JK29LP)4 people · 5 mentions · first linked 2016-07-26
- /2020/05/pre-calculated-line-breaks-for-html-css/4 people · 4 mentions · first linked 2020-05-25
- /2015/05/amazon-dash-button-teardown/2 people · 2 mentions · first linked 2016-05-12
- Scanner Modifications to Scan Large Documents (2013)2 people · 2 mentions · first linked 2019-11-19
- /2012/09/kindle-weather-display/2 people · 2 mentions · first linked 2016-06-13
- Kindle Weather Display [2012]2 people · 2 mentions · first linked 2015-06-17
What Hacker News says?
The comment is invalid CSS to apply the Knuth-Plass algorithm in rendering an HTML article. Knuth being a perfectionist’s perfectionist, TeX uses this algorithm to determine optimal line breaks to provide for better text justification. Here’s a discussion of hacks to achieve the algorithm’s results on web pages and an upcoming CSS feature as of 2020. https://mpetroff.net/2020/05/pre-calculated-line-breaks-for-...
Comment linking /2020/05/pre-calculated-line-breaks-for-html-css/
on “ArXiv now offers papers in HTML format”Submitted Kindle Weather Display as a story · 12 points
HN discussionThis had me wondering about whether it was possible to use pre-calculated line breaks to implement improved text justification in current browsers. I was able to come up with a demo [1][2] that does so, although it falls back to default line breaks in Safari due to lack of support for `text-align-last`. [1] https://mpetroff.net/files/pre-calculated-line-breaks-demo/ [2] https://mpetroff.net/2020/05/pre-calculated-li…
Comment linking /2020/05/pre-calculated-line-breaks-for-html-css/
on “Show HN: LaTeX.css – Make your website look like a LaTeX document”Submitted Hilbert Curve Cake as a story · 3 points
HN discussionHere's an analysis of the colorblind-friendliness of Turbo and other colormaps: https://mpetroff.net/2019/08/discernibility-of-rainbow-color...
Comment linking /2019/08/discernibility-of-rainbow-colormaps/
on “Turbo, an Improved Rainbow Colormap for Visualization”Submitted New Amazon Dash Button Teardown (JK29LP) as a story · 3 points
HN discussionYeah, I find it hard to believe this device could be sold for $4.99 at a profit, if you count up BOM, assembly and logistics related to sending it. But given that some posters mention Amazon actually gives you $4.99 back for the first purchase, they must not be caring. Anyway, here's a teardown I found: https://mpetroff.net/2015/05/amazon-dash-button-teardown/ Now a surprising thing that I didn't know before - this…
Comment linking /2015/05/amazon-dash-button-teardown/
on “3-D printed plastic objects that can communicate with WiFi devices”Submitted Kindle Weather Display [2012] as a story · 3 points
HN discussionThe issue isn't with referring to colors on a chart by name but with using a color name as the sole identifier. Referring to parts of a chart by color is fine, and provides additional information, as long as a line style or shape identifier is also used, e.g., the "blue solid line" and the "orange dashed line" in the case of a line plot or the "blue circles" and the "orange squares" in the case of a scatter plot. Id…
Comment linking /2019/11/figure-caption-color-indicators/
on “Color blindness”Submitted Scanner Modifications to Scan Large Documents (2013) as a story · 2 points
HN discussionSounds cool, easy, and cheap. Not sure what I would do with it. Here is a tear down: http://mpetroff.net/2015/05/amazon-dash-button-teardown/ I can't find how long the battery lasts and with only one AAA, it might not be that long.
Comment linking /2015/05/amazon-dash-button-teardown/
on “How I Hacked Amazon’s $5 WiFi Button”Submitted Scanner Modifications to Scan Large Documents (2013) as a story · 1 points
HN discussionThis is interesting, since from teardowns it looks like there's literally just a AAA battery in there: https://mpetroff.net/2015/05/amazon-dash-button-teardown/
Comment linking /2015/05/amazon-dash-button-teardown/
on “AWS IoT Button”Submitted Color cycle survey: preliminary order ranking results as a story · 1 points
HN discussionThis guy did that (sort of, but he keeps the Kindle running): https://mpetroff.net/2012/09/kindle-weather-display/ , does the Kindle have a power-on timer?
Comment linking /2012/09/kindle-weather-display/
on “E-ink wifi display project”Submitted Preliminary Color Cycle Set Ranking Results as a story · 1 points
HN discussionNote that Amazon rolled out a second revision of the Dash button that is 4x more energy efficient: "I measured the new Dash Button’s energy usage to be 4.3±2.2 J per activation and the original Button’s energy usage to be 16.4±0.1 J per activation." Source: https://mpetroff.net/2016/07/new-amazon-dash-button-teardown... Although the Dash is still much over-engineered: for every activation it has to establish (I beli…
Comment linking /2016/07/new-amazon-dash-button-teardown-jk29lp/
on “Why I stopped hacking the Amazon Dash button and learned to solder”Yes and yes https://mpetroff.net/2016/07/new-amazon-dash-button-teardown... New one also uses 4x less power, cheaper battery lasts twice as long
Comment linking /2016/07/new-amazon-dash-button-teardown-jk29lp/
on “Why I stopped hacking the Amazon Dash button and learned to solder”It's possible, but the markup is very, very messy. I made a proof-of-concept by hand a couple months ago [1], but it would require quite a bit more work to automate it. It's probably best to just wait for browsers to implement CSS Text Module Level 4, which includes a property for enabling use of better line breaking algorithms. [1] https://mpetroff.net/files/pre-calculated-line-breaks-demo/
Comment linking /files/pre-calculated-line-breaks-demo/
on “Perfect Edition: A lightweight, responsive web e-book template”I remember a similar looking project from a few years ago fwiw: https://mpetroff.net/2012/09/kindle-weather-display/ Another, inspired by that: https://shkspr.mobi/blog/2020/02/turn-an-old-ereader-into-an... A little off topic, but for anybody interested in doing something for themselves, there are various "smart mirrors" that aren't e-ink, but use a tablet screen behind a mirror. Eg. https://www.instructables.com/h…
Comment linking /2012/09/kindle-weather-display/
on “Paperd.Ink – A hackable e-paper display”> The key would be to spend an absurd amount of time carefully cataloguing good colors – by hand – and training it to extrapolate from that information. It's a bit more nuanced than that. Not only do you need to catalog good colors (and color combinations), you need to have it done by a large number of people, since different people perceive color differently and have different aesthetic preferences. This is somethi…
Comment linking /2020/01/color-cycle-survey-update/
on “Show HN: AI color palette generator for Tailwindcss”For anyone interested in weird low cost embedded devices, I suggest googling for Amazon dash button teardowns. There's some interesting choices made in their components and spec. https://mpetroff.net/2016/07/new-amazon-dash-button-teardown... https://www.edn.com/design/consumer/4460866/Teardown--Design... There is also this thing, the Amazon wand: https://www.edn.com/design/consumer/4460319/Teardown--Amazon...
Comment linking /2016/07/new-amazon-dash-button-teardown-jk29lp/
on “Amazon will pull the plug on dash buttons”Neat, reminds me that I want to turn an older one into an uptime / analytics monitor sorta like this: http://mpetroff.net/2012/09/kindle-weather-display/
Comment linking /2012/09/kindle-weather-display/
on “Kindle Paperwhite”Possibly this: https://mpetroff.net/2020/05/pre-calculated-line-breaks-for-...
Comment linking /2020/05/pre-calculated-line-breaks-for-html-css/
on “Knuth and Plass line-breaking Revisited”One immediately wonders about using it in browsers, but I looked into this a fair bit and concluded that there doesn't seem to be any viable approach still if you have real web content (rather than short toy blog posts), care about performance, and want Knuth-Plass: https://gwern.net/design-graveyard#knuth-plass-line-breaking But props to https://mpetroff.net/2020/05/pre-calculated-line-breaks-for-... for a cool hac…
Comment linking /2020/05/pre-calculated-line-breaks-for-html-css/
on “Knuth and Plass line-breaking revisited (2007)”That's what Amazon's IoT button is. A more expensive Dash button that you can control. https://aws.amazon.com/iotbutton/ "Control", though, doesn't mean source code for the device, but rather, programmatic control over the endpoint (Lambda, etc). "You can code the button's logic in the cloud " The first gen STM32 based Dash buttons were hackable[1], but Amazon changed to a different platform (ATMEL[2]) and locked th…
Comment linking /2016/07/new-amazon-dash-button-teardown-jk29lp/
on “Show HN: Send a slack msg with AWS IoT button”
