It's School time: Adventures in hacking an old Kindle
11 comments
·April 28, 2025mtlynch
>I designed a backend API that collected the data in real-time data and exported it as a PNG image.
Does anyone know why in these Kindle modding dashboards, they always generate the dashbard image on an external server? Why isn't it possible to build all that functionality into an executable on the Kindle itself? You've got a Linux environment, so why can't you run all the logic locally?
kovac
I built this dashboard. The price curves and text are rendered locally from the microcontroller and painted pixel by pixel. Letters use raster fonts stored locally, price curves are generated on the fly. It can be done, it takes a bit of care. Mine only has ~400KB memory. It must be a lot easier on the Kindle, I think it runs Java even.
dmitrygr
Most people today do not know how to program in the confines of 256MB of RAM and are not aware that languages other than javascript exist.
supportengineer
I expected the Kindle to do a few api calls and call ImageMagick but instead, in Cloudflare, it sets up a headless browser, and renders a web page to a PNG file on the server, and then only the final png image gets returned to the Kindle.
gitroom
lol i get weirdly obsessed with decimal places on stuff like this too - makes me laugh every time.
mahi_novice
Love this! Always fun to do stuff like this.
dmitrygr
4 significant figures on weather temperature is kind of funny to look at. Must be some very accurate forecasts
mobilemidget
I was just here to write the same thing :) imagine it being 0.01 degrees too warm or cold
alnwlsn
Reminds me of those times I work with temperature sensors which report in eighths of a degree. 3 decimal places to give less than one decimal place of precision. You can round, but somehow that doesn't feel right.
null
In case the author ever sees this...
If you have that battery level available off the Kindle, you can use it to turn a wifi "smart plug" on and off, to automatically top the charge up only when required.
(Or, more old-school, use a powerpoint timer set to only power up for a short time each day. I did this way back, when the place I worked decided they needed iPads stuck next to meeting room doors to stop arguments about who had it booked, but when they first installed them they left them plugged into the charger 24x7, and the batteries in them would puff up in 8-12 months and kill the iPads. Putting the charger in a timer so they only charged hour a day saved them about $6,000 a year in puffed up iPads.)