Embedded firmware · Reverse engineering · Audio SoCs · PCB design
_{Türkiye · building at @OmfoBalkanMicroElectronics}

barbaror4@bench:~$ whoami
Firmware developer who takes cheap, undocumented chips apart
and makes them do things their datasheets never promised.

I work on embedded systems from the bare metal up: reading datasheets, dumping firmware, tracing undocumented SDKs, and designing the boards to run it all on. My main focus is JieLi audio SoCs, plus STM32 and other low-cost platforms that deserve more attention than they get.

Custom firmware and hardware for the JieLi AC6925 (AC692x), a Bluetooth audio SoC with 128 KB of RAM and 512 KB of flash that normally runs cheap speakers. MagicJL turns it into a full media player, one generation at a time:

_{MagicJL Plus on real hardware (BT201, AC6925A, SSD1306 OLED)}

_{MagicJL Color 2.0, rendered by the PC simulator from the firmware's own GUI code}

Custom boards for the platform:

 
_{MagicJL UNO (Arduino UNO–sized dev board) · MagicJL PLUS board (AC6921A8 + SH1106 SPI OLED, the hardware target for MagicJL Plus)}

Retro gaming and multimedia on the STM32F746G-DISCO: NES emulation, DOOM and Wolfenstein 3D, an MP3/FLAC player with FFT, Motion-JPEG video and exFAT support on a Cortex-M7.

The repository is private for now while its third-party licensing (bundled libraries, fonts and assets) is being cleaned up. It will be public again once that's done.

Linux 2.6.33 (uClinux / NOMMU) running on the STM32F746G-DISCO, with an SD-card root filesystem, USB-HID keyboard host and Ethernet. Real Linux on a microcontroller with no MMU.

Open-source, cross-platform music visualizer and VJ tool (Electron + WebGL, MilkDrop engine, GPU effects, OBS overlay, RGB lighting).

• Stereo Trails visualizer mode (PR #732, in review): a particle fountain where each frequency band launches from its place in the stereo image. Per-band biquad filters measure pan and stereo spread (correlation) in about 0.07 ms per frame, covered by 16 new tests that caught all 10 deliberately injected bugs.
• Floating picture-in-picture output window, proposed and prototyped in PR #592 and now part of the app
• Reverse-engineered Pioneer's .lkd OEL animation format (gzip → tar → stacked BMP strip), verified against 83 real files

• JieLi: AC692x firmware, SDK internals, custom boards
• STM32: F103 · F411 · F746
• Espressif: ESP32 · ESP8266
• Displays: SSD1306 OLED · ST7920 · ST7789 IPS
• Others: NationalChip / GuoXin, Generalplus, PIC, AVR

├── JieLi AC692x firmware & SDK development
├── Reverse engineering undocumented SoCs and firmware
├── Embedded audio: USB Audio, codecs, DACs, FFT, parametric EQ
├── Embedded GUIs: frame-buffer-less rendering, SPI DMA displays, PC simulators
├── STM32 peripherals, DMA and real-time systems
├── Embedded Linux on NOMMU targets
└── Custom PCB design

I use the hardware I have and learn from datasheets, source code, experiments and a lot of reverse engineering.

Expensive ≠ Interesting
Old ≠ Useless
Cheap ≠ Simple

Understand it. Modify it. Push it further.



Hardware is more fun when you dig deeper.