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stm32dev

STM32H7 touch-screen board notes, ST-Link/OpenOCD scripts, and persistent framebuffer patch source.

stm32dev is a practical workspace for a connected STM32H74/H75 touch-screen board. It records the wiring, host setup, ST-Link control commands, flash backup/restore workflow, minimal firmware scaffold, and the assembly source for a persistent RGB565 framebuffer hook.

This public repository intentionally excludes generated binaries, flash dumps, local build output, and downloaded tool archives. Those files are hardware-specific and can be recreated or kept locally when needed.

Display Preview

Contents

Path	Purpose
scripts/	Probe, OpenOCD, flash backup/restore, explicit binary flash, and serial-listen helpers.
docs/wiring.md	SWD, UART, power, and Type-C notes for the board.
config/49-stm32-stlink-local.rules	Local udev rules for ST-Link permissions and password-prompt avoidance.
firmware/minimal/	Minimal Cortex-M7 STM32H7 firmware scaffold for toolchain validation.
firmware/persistent_trio/	Thumb assembly hook and linker scripts used for the persistent display patch.
references/stm32-touch-board-session.md	Session log with target identification, commands, addresses, cache notes, and restore path.

Quick Start

Probe the board:

./scripts/probe.sh

Start OpenOCD:

./scripts/openocd.sh

Back up flash locally:

./scripts/backup_flash.sh

Restore a local firmware backup:

./scripts/restore_flash.sh backups/stm32h7_current_flash_2026-06-19.bin

Build the minimal firmware scaffold:

make -C firmware/minimal

Persistent Display Patch

The board was identified as an STM32H74/H75 target with a 1024x600 RGB565 LTDC framebuffer at 0xC0000000. The persistent image experiment stores RGB565 data in unused flash regions and hooks a firmware delay routine so the display framebuffer is restored after boot.

The final working hook:

• returns to 0x08001325, preserving Thumb mode;
• checks that LTDC layer 1 points at 0xC0000000;
• invalidates sample D-cache lines before checking SDRAM-visible pixels;
• copies two flash image segments into SDRAM when the framebuffer has been cleared;
• cleans the full framebuffer D-cache range so LTDC can read the CPU-written image.

The detailed addresses and verification hashes are in references/stm32-touch-board-session.md.

Public Release Notes

The public repo keeps source and documentation only. These local paths are ignored:

• backups/
• build/
• **/build/
• *.bin, *.elf, *.map, *.o, *.d, *.log
• downloaded or extracted xPack tool directories under tools/

Do not flash test firmware unless overwriting the currently installed touch-screen firmware is intentional.

Validation

Commands used during development:

st-info --probe
openocd -f interface/stlink.cfg -f target/stm32h7x.cfg -c 'adapter speed 1000' -c 'init' -c 'targets' -c 'shutdown'
make -C firmware/minimal

Citation

If you use stm32dev in research or documentation, cite this repository. GitHub reads CITATION.cff and shows a Cite this repository panel on the repo page.

@software{chen_stm32dev_2026,
  author = {Chen, Lachlan},
  title = {stm32dev: STM32H7 Touch-Screen Board Development Workspace},
  year = {2026},
  url = {https://github.com/lachlanchen/stm32dev}
}

Status

This is a hardware-session workspace, not a vendor board support package. It is useful as a reproducible record for ST-Link/OpenOCD control, framebuffer experiments, and STM32H7 cache-aware display patching.

Support

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