JR · @dniminenn
I build things that have to be measurably correct.
Notes on precision timing, audio, embedded systems, and debugging by measurement. Most of these started as an idle question and ran further than they had any right to.
Precision timing
GPS-disciplined clocks, NTP and PTP, nanosecond budgets, and proving a clock is honest.
Audio, end to end
Bit-perfect playback paths, DSP, LED visualizers, and chasing latency you can hear.
Embedded systems
ESP32, RP2040, and the firmware that has to keep running when the network does not.
Systems debugging
Reading the kernel, tracing the wire, measuring instead of guessing.
Selected writing
Reverse engineering the Attack Shark keyboard protocol
Attack Shark, Epomaker and Akko sell hundreds of keyboards built on the same ROYUAN hardware, configurable only through Windows software. Here is the wire protocol: two colliding command sets, per-key colour that lands in flash, and a firmware image read out of a rescued binary.
The load average with a seven hour heartbeat
Every seven hours the router's load average hit 1.0 for forty five minutes. CPU was 98% idle. Nothing ran, nothing blocked, nothing was stolen. The culprit was a beat frequency between two five second clocks, and one of them was mine.
A fork in the uncanny valley
Working with an AI on a side project, it felt more authentic and more obviously not human at the same time. That is not what the uncanny valley predicts. A case that the road forks, and that off-axis is the better direction to be heading.
Putting back the bass that was never recorded
I prepped a music set for a 1500-watt DIY rig and synthesized a missing sub-bass octave into tracks rolled off below 40 Hz. Measure first, fix only what the numbers justify, don't touch anything else.