STM32H7S78-DK Audio Effects Processor

Project Overview

This dual-boot project consists of two components working together to create a professional audio effects processor:

Key Features

• Real-time audio effects processing at 48kHz sample rate
• 6 audio effects: Octaver, Equalizer, Overdrive, Saturation, Echo, Reverb
• 2048-point FFT spectrum analyzer with 1024 frequency bins
• Audio looper with up to 5 seconds recording (2x playback speed)
• TouchGFX graphical interface with NemaGFX GPU acceleration
• Dual-boot architecture for reliable firmware updates

System Architecture

Dual-Boot Structure

This project uses a dual-project architecture:

Flashing Sequence

Important: The Appli uses external memory (0x70000000) for TouchGFX assets and requires the external FlashLoader MX66UW1G45G_STM32H7S78-DK.stldr to program the external flash.

Build System

Build System: GCC Makefile (not CMake)

Toolchain: gcc-arm-embedded (arm-none-eabi-gcc)

IDE: STM32CubeIDE with STM32CubeMX plugin

Real-Time Operating System

RTOS: FreeRTOS V10.5.1 (CMSIS-RTOS V2)

Heap Size: 50KB (heap_4)

Task priorities: Audio interrupts at priority 2 (high), touch/SD at 14-15

Hardware Specifications

Core Hardware

Audio Peripherals

Display & Touch

Storage & Communication

Build & Flash Guide

Prerequisites

• STM32CubeIDE (for CubeMX GUI, code generation)
• gcc-arm-embedded (arm-none-eabi-gcc)
• STM32CubeProgrammer (for flashing with external loader)
• TouchGFX 4.26.1 (for GUI generation)

Build Commands

From the project root directory:

# Build both Boot and Appli
make

# Clean all build artifacts
make clean

# Build only Boot
make -f gcc/makefile_boot all

# Build only Appli
make -f gcc/makefile_appli all

Flashing Commands

Important: Flashing requires external FlashLoader for external memory access.

Flash Boot (internal flash only)

STM32_Programmer_CLI -c port=SWD \
  -d Boot/TouchGFX/build/bin/target.hex \
  -hardRst

Flash Appli (requires external FlashLoader)

STM32_Programmer_CLI -c port=SWD \
  -d Appli/TouchGFX/build/bin/target.hex \
  -el gcc/MX66UW1G45G_STM32H7S78-DK.stldr \
  -hardRst

VS Code Tasks

Two VS Code tasks are available in .vscode/tasks.json:

• Build + Flash Boot - Builds and flashes the Bootloader
• Build + Flash Appli - Builds and flashes the Application with external loader

Note: The Flash Loader for external memory is located at: gcc/MX66UW1G45G_STM32H7S78-DK.stldr

Debugging Guide

Debugging the code in an IDE can be complex because of the Bootloader and Application structure. To step through the code of the TouchGFX application in STM32CubeIDE, follow these steps:

Command Line Debugging

# Terminal 1: Start GDB server
openocd -f interface/jlink.cfg -f target/sth7rs.cfg

# Terminal 2: Connect with GDB
arm-none-eabi-gdb gcc/target.elf
(gdb) target remote :3333
(gdb) load
(gdb) break main
(gdb) continue

Audio Processing

Effects Chain

The audio effects are processed in the following order:

Spectrum Analyzer

AudioLooper

Memory Map

TouchGFX Architecture

Project Structure

Appli/
└── TouchGFX/
    ├── App/                    # Application code (user created)
    ├── assets/                 # Images, fonts, videos
    ├── build/                  # Generated build files
    │   └── bin/
    │       ├── target.hex      # Flash image (INTERNAL)
    │       └── target.bin      # Binary image (EXTERNAL)
    ├── config/                 # Build configuration
    ├── generated/              # Auto-generated code (DO NOT EDIT)
    ├── gui/                    # Custom GUI code (views, presenters)
    │   ├── views/              # Screen views
    │   ├── presenters/         # Presenter logic
    │   └── model/              # Model data
    ├── simulator/              # Simulator files
    └── target/                 # Target-specific code

GUI Screens

TouchGFX Architecture

• Views: UI screen implementations
• Presenters: Business logic between views and model
• Model: Data storage and state management
• Assets: Images, fonts, videos stored in external flash

GPU Acceleration

The application uses NemaGFX (GPU2D) for accelerated 2D rendering:

• Alpha blending
• Image scaling
• Color format conversion
• Windowed rendering

Troubleshooting

Common Build Issues

Verification Commands

# Verify internal flash (Boot)
STM32_Programmer_CLI -c port=SWD -u 0x08000000 0x1000 /tmp/read_int.bin

# Verify external flash (Appli)
STM32_Programmer_CLI -c port=SWD -u 0x70000000 0x1000 /tmp/read_ext.bin

Flashing Checklist