Custom Snapmaker U1 Firmware

RFID Filament Tag Support

Available in: All firmware (extended adds OpenSpool support)

The Snapmaker U1 automatically detects filament properties by reading RFID tags on spools.

Firmware Support:

Original & Basic: Mifare Classic 1K with Snapmaker proprietary format
Extended: Adds NTAG215/216 support with OpenSpool format

Supported Formats

Feature	OpenSpool 🏆	OpenPrintTag	OpenTag3D	Snapmaker
Tag Type	NTAG215 (540 bytes) / NTAG216 (888 bytes)	ISO15693/SLIX2	NTAG215/216 or ISO15693/SLIX2	Mifare Classic 1K
Encoding	JSON (NDEF)	CBOR (NDEF)	Binary	Proprietary + RSA signature
Data Format	Human-readable JSON	Compact CBOR binary	Binary	Encrypted proprietary
Specification	openspool.io	specs.openprinttag.org	OpenTag3D	Proprietary (closed)
GitHub Repository	spuder/OpenSpool	prusa3d/OpenPrintTag	queengooborg/OpenTag3D	N/A
Popularity	⭐⭐⭐ (623 stars)	⭐⭐ (213 stars)	⭐ (17 stars)	N/A
Programming Tools	Any NDEF-capable NFC app	Prusa app only	opentag3d.info/make	Snapmaker official only
U1 Compatible	✅ Yes (extended firmware)	❌ No (ISO15693 not supported)	⚠️ Not implemented yet	✅ Yes (all firmware)
Ease of Programming	Easy (any NFC app)	Medium (requires Prusa app)	Medium (web-based tool)	Hard (official tags only)
Data Portability	High (simple JSON)	High (open CBOR spec)	Medium (binary format)	None (proprietary)

🏆 = Recommended for U1 (NTAG215 is the sweet spot for capacity and compatibility)

How It Works

Tags are automatically read when filament is loaded into the feeder. Tag data clears when filament is removed.

Manual Commands:

Read tag: FILAMENT_DT_UPDATE CHANNEL=<n>
Clear tag data: FILAMENT_DT_CLEAR CHANNEL=<n>
Check current tag: FILAMENT_DT_QUERY CHANNEL=<n>

Programming Filament Tags

OpenSpool (Recommended for Extended Firmware)

Quick Setup:

Get NTAG215 or NTAG216 tags
Open Chrome on Android phone
Visit printtag-web.pages.dev
Enter filament information
Tap tag to phone to write

Alternative: Use any NFC app that supports NDEF with JSON (MIME type: application/json)

Example payload:

{
  "protocol": "openspool",
  "version": "1.0",
  "brand": "Generic",
  "type": "PLA",
  "color_hex": "#FF0000",
  "min_temp": 190,
  "max_temp": 220,
  "bed_min_temp": 50,
  "bed_max_temp": 60
}

Using the non-standard OpenSpool subtype field it is possible to specify a material subtype:

{
  "protocol": "openspool",
  "version": "1.0",
  "type": "PETG",
  "subtype": "Rapid",
  "color_hex": "AFAFAF",
  "additional_color_hexes": ["EEFFEE","FF00FF"],
  "alpha": "FF",
  "brand": "Elegoo",
  "min_temp": "230",
  "max_temp": "260"
}

OpenSpool Field Reference

Required Fields:

protocol - Must be “openspool”
version - Specification version (e.g., “1.0”)
type - Material type (PLA, PETG, ABS, TPU, etc.)
color_hex - Color in hex format (#RRGGBB)

Optional Standard Fields:

brand - Manufacturer name
min_temp / max_temp - Nozzle temperature range in °C

Optional Extended Fields (U1-specific):

bed_min_temp / bed_max_temp - Bed temperature range in °C
subtype - Material variant (Basic, Rapid, HF, Silk, etc.)
alpha - Color transparency (00-FF hex, default: FF)
additional_color_hexes - Additional colors for multicolor spools (up to 4)
weight - Spool weight in grams
diameter - Filament diameter in mm (e.g., 1.75)

Snapmaker Orca Naming Convention

Snapmaker Orca requires filaments to follow this naming pattern: <brand> <type> <subtype>

Examples: Generic PLA Basic, Elegoo PETG Rapid

Reading Existing Tags

Use the NFC Tools app (iOS/Android) to inspect tags:

Download NFC Tools from App Store or Google Play
Tap “Read” and hold tag to phone
Check tag type and NDEF records

Compatible tag types: NTAG213/215/216, Mifare Classic 1K Note: ISO15693 tags (OpenPrintTag) are not supported

Troubleshooting

Tag not detected:

Ensure tag is NTAG213/215/216 or Mifare Classic 1K
Position tag within 1-3cm of reader antenna
Manually read tag: FILAMENT_DT_UPDATE CHANNEL=<n> then FILAMENT_DT_QUERY CHANNEL=<n>
Check klipper.log for detection messages

OpenPrintTag tags don’t work:

Expected - OpenPrintTag uses ISO15693 which is not supported by U1 hardware
Use NTAG tags with OpenSpool format instead

NTAG tags only work on extended firmware:

Basic and original firmware only support Mifare Classic 1K with Snapmaker proprietary format
Extended firmware adds NTAG215/216 support