gbt — Ghost Build Tool

Build and package GhostESP native SD apps from the command line.

Install

pip install ghostbt

Requires Python 3.10+ and ESP-IDF (install via gbt setup).

Quick Start

# Set up ESP-IDF (one-time)
gbt setup

# Create a new app
gbt create my_app --name "My App"

# Build and package
gbt dist ./my_app --gapp

# Flash firmware to device
gbt firmware cardputer
gbt flash firmware --board cardputer --monitor

Commands

Asset Packs

Create a source folder with a manifest.json and PNG artwork. gbt asset pack converts source images into compact .gimg files and writes a runtime manifest for /mnt/ghostesp/themes/<pack id>/.

{
  "id": "cyberpack",
  "name": "Cyber Pack",
  "version": 1,
  "colors": {
    "accent": "0xFF00FF",
    "background": "0x0A0A0A",
    "surface": "0x1A0A1A",
    "surface_alt": "0x2A1A2A",
    "text": "0xFFFFFF",
    "text_muted": "0xAA88CC"
  },
  "icon_variants": [32, 64],
  "icon_sources": {
    "wifi": "art/icons/wifi.png",
    "bluetooth": "art/icons/bluetooth.png",
    "settings_icon": "art/icons/settings.png"
  },
  "background_sources": {
    "bg_tile": {
      "source": "art/bg_tile.png",
      "width": 64,
      "height": 64,
      "format": "rgb565"
    }
  }
}

Build it:

gbt asset pack ./cyberpack --out ./dist
gbt asset pack ./cyberpack --out ./dist --archive

Install a generated pack folder by copying it to SD as:

/mnt/ghostesp/themes/cyberpack/manifest.json
/mnt/ghostesp/themes/cyberpack/icons/...

Or install an archive by copying the .gtheme to SD as:

/mnt/ghostesp/themes/cyberpack.gtheme

Then use Settings > Appearance > Asset Pack and press left/right to cycle installed packs. Firmware scans /mnt/ghostesp/themes/ for pack folders with manifest.json and for .gtheme archives. The selected pack is saved in NVS.

When loading a .gtheme, firmware streams entries into /mnt/ghostesp/themes/active/ before loading. New .gtheme archives store raw .gimg payloads without deflate compression for safe runtime decoding. Theme SD access uses the same short mount/unmount flow as other SD operations; decoded icons and background tiles stay cached in RAM/PSRAM after each read.

PSRAM vs internal RAM

PSRAM devices: Up to 32 icons cached in PSRAM, tiled or scaled backgrounds supported. Background images smaller than the screen tile automatically; larger images scale to fill using LVGL zoom. A 128x128 background will scale up to fill any screen. Background images are always loaded into PSRAM. Any image format works; deflate-compressed payloads decode into PSRAM.

Internal-only devices: 2 icons cached in internal RAM. Background tile (≤32x32) supported — LVGL tiles the small image across the screen. Icon size capped at 32x32 RGB565A8; deflate-compressed payloads rejected. Use the indexed_4bpp format for icons and the background tile to fit in internal RAM: a 32x32 indexed icon is 576 bytes vs 3,072 bytes for RGB565A8 (~5x smaller). Icons fall back to compiled-in artwork when the cache is full. The pack still loads colors and icon mappings; only the image cache is limited.

Image formats

Set the pack-wide icon format with icon_format in the source manifest, or override per-background via the format field on each background_sources entry. Indexed payloads are always stored uncompressed.

Convert one image directly:

# Default — RGB565A8, 3 KB for 32x32
gbt asset image ./wifi.png --out ./wifi_l.gimg --width 64 --height 64 --format rgb565a8

# Internal-RAM friendly — indexed 4bpp, 576 B for 32x32
gbt asset image ./wifi.png --out ./wifi_l.gimg --width 64 --height 64 --format indexed_4bpp

The generated pack folder contains manifest.json, checksums.json, and generated .gimg files. Asset packs store raw .gimg payloads by default so firmware does not run deflate decompression from small UI task stacks. Missing icons are fine; firmware falls back to built-in artwork for any icon not present in the selected pack. Full-screen background images are loaded into PSRAM only; the smaller tiled background path works on internal-RAM devices at ≤32x32.

Requirements

• Python 3.10 or later
• ESP-IDF (auto-installed by gbt setup if missing)
• Git (for gbt setup)

Links

• GhostESP GitHub
• Full documentation