Thanassis Tsiodras writes about embedded and low-level projects, including FPGAs, ASN.1, Reed-Solomon coding, Android hacking and retro music players.
HN links it for hardware projects like compiling a SPARC CPU on a cheap FPGA, and for an ASN.1 article comparing it to JSON.
Sorry, I misremembered, the native flicker frequency is at 200 Hz, I had to look up my notes again and verify by listening to my solar panel hooked up to a 3.5mm jack.
I forgot to mention, I actually managed to write a program that would dynamically rewrite the period and pulse width registers to play music off the screen backlight, based off a conversion of the Monkey Island tunes from https://www.thanassis.space/monkeyisland.html. It almost worked... except that whenever I decreased the period (raised the pitch), there was a random chance the new period would be greater than the current phase, and so the display would hang at full or zero brightness nonstop (producing a gap in the sound) until the 16-bit counter running at 0.98 MHz (= 125/128) rolled over, rather than instantly setting the counter to zero and turning the display back on. I've recorded my "best effort" attempt at music, at https://www.youtube.com/watch?v=7qt0ssFk410 (every recording has different gaps when pitch increases).
As soon as I met Forth, I felt I had to hack my own (https://github.com/ttsiodras/MiniForth/) - and did so over a single week, two years ago. I targeted the Blue Pill and the original Arduino, but developed via cross-compilers so that I could test my code in the host.
I became so obsessed with the project that I was looking forward to tinkering with it after coming back from work every day; so it was hacked in 5 evenings and a weekend.
It was that much fun, to build a Forth.
I highly recommend the process; I think the only other time I felt so enlightened was when I first met Lisp macros (https://www.thanassis.space/score4.html#lisp).
In this HN article:
Compiling my own SPARC CPU inside a cheap FPGA:
https://news.ycombinator.com/item?id=21303446
(https://www.thanassis.space/myowncpu.html)
Thanassis Tsiodras takes an old, cheap Pano Logic G2 (thin client hardware box), and repurposes its FPGA to create a custom CPU...
Well, I'm curious... what other cheap FPGA-containing products might there be out there?
Driving a lot of LEDs: https://mobile.twitter.com/GregDavill/status/1192515630626291712
Processing video (especially if you have weird requirements like 14 bit greyscale input): https://gregdavill.com/blog/2018/9/9/boson-camera-project-part-4
Experimenting with non-mainstream CPUs:
https://www.thanassis.space/myowncpu.html
https://github.com/cliffordwolf/picorv32
There is an excellent article about ASN.1 and how it relates to JSON and other forms of encoding.
Here: https://www.thanassis.space/asn1.html