Framebuffer Dump

Framebuffer Dump (J-Link → PNG)

Export the actual on-device rendered frame directly from SDRAM framebuffer and convert to PNG.

Default parameters (PRO2)

• Device: STM32H747XI_M7
• FB base: 0xD0000000
• Resolution: 604x1024
• Pixel format: RGB888 (3 bytes/pixel)
• Dump size: 604*1024*3 = 1,855,488 (0x1C5000)

One-shot workflow

1) Create J-Link command file

Use scripts/dump_fb.jlink.template and replace placeholders:

• {{DEVICE}}
• {{SPEED_KHZ}} (e.g. 12000)
• {{OUT_BIN}} (absolute path)
• {{FB_ADDR}} (e.g. 0xD0000000)
• {{FB_SIZE}} (e.g. 0x1C5000)

2) Dump raw framebuffer

JLinkExe -NoGui 1 -CommandFile /tmp/jlink_dump_fb.jlink > /tmp/jlink_dump_fb.log 2>&1

3) Convert raw to PNG

python3 scripts/dump_fb.py \
  --in /path/to/fb_dump.bin \
  --out /path/to/fb_dump_604x1024.png \
  --width 604 --height 1024 --stride 3

Troubleshooting

• If output bin is 0 bytes: check J-Link connection / path permissions.
• If colors look wrong: verify pixel format is RGB888 (not BGR / RGB565).
• If image shifted/corrupt: verify width/height match current display mode.
• If command hangs too long: make sure dump size is correct (0x1C5000 for 604x1024 RGB888).

Notes

• This method captures real framebuffer pixels (no camera distortion).
• Best for Figma-vs-device pixel comparison and regression snapshots.