hIRoic

Real-time guitar cabinet impulse response (IR) convolution processor running on the STM32F746G Discovery board, built with Zephyr RTOS.

Features

• Real-time IR convolution using CMSIS-DSP (overlap-save, FFT-based)
• WAV IR loading from SD card (PCM, 16/24/32-bit, up to 1048 samples)
• WM8994 audio codec driver (I2S, 44.1 kHz, 32-bit)
• LVGL display with VU meter and IR name
• Serial console for IR cycling and bypass control

Hardware

• Board: STM32F746G-DISCO
• Codec: WM8994 (on-board)
• Storage: microSD card with WAV files in root directory

Building

Requires a Zephyr workspace.

source /path/to/zephyrproject/.venv/bin/activate
west build -b stm32f746g_disco /path/to/hIRoic_zephyr --pristine
west flash --runner openocd

Usage

Place .wav IR files on a FAT-formatted microSD card and insert it into the board. Use the serial console (115200 baud):

• a - Load next IR
• s - Toggle bypass (dry signal passthrough)

Project Structure

src/
  main.c          - Threads (audio, input, heartbeat), I2S streaming, LVGL UI
  dsp.c/h         - FFT-based overlap-save convolution (CMSIS-DSP)
  ir_manager.c/h  - SD card mounting, WAV file enumeration, IR loading
  wav_parser.c/h  - WAV file parsing with struct-cast approach
  app_conf.h      - DSP and buffer configuration constants
drivers/
  wm8994/         - Out-of-tree Zephyr audio codec driver for WM8994
boards/
  stm32f746g_disco.conf     - Kconfig for the target board
  stm32f746g_disco.overlay  - Devicetree overlay (I2S, SD card, codec)

License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.

Copyright (C) 2026 Kamil Lulko kamil.lulko@gmail.com