6d9a49ea42
The SKU<->EPC layout inherited from daemon.cs was WRONG. daemon.cs packs 6 bytes
of SKU + 4 bytes of release_id + an 0xEC01 marker, and flagged itself as
unverified. The shop's actual scheme -- in pliceclogs/rfid-daemon/index.js
(buildEpcPayload/parseEpcData), which is what the extension and every existing
tag use -- is a single 96-bit big-endian integer:
value = sku(14 digits) * 10^9 + releaseId
Checked against that file's own worked example: 20260321001001 + 35332 ->
20260321001001000035332. epc_decode also reproduces its guard, returning None
when value/10^9 exceeds 14 digits, so a factory tag (E28069...) can never be
reported to the operator as a real SKU.
This matters: parseEpcData rejects the EC01 layout outright, so every tag the
Windows daemon has written is invisible to the extension. ASSESSMENT.md now
carries that as a red open item against daemon.cs.
Verified end-to-end with an INDEPENDENT reader. ASSESSMENT.md sec.4 parked the
Chafon as HID-keyboard-only, but that is Windows-specific -- on macOS it exposes
a CH340 bridge and its documented serial protocol works. New chafon.py (read-only:
inventory + read EPC, CRC-16/0x8408 framing) scans the field and sees:
0000044A5600D4CDA1FAB932 -> sku=20260722180000 rel=424242 (Urovo-written)
E28069950000600625F600D3 -> factory/blank (x12, rest of roll)
126D5125FFA000067932EC01 -> factory/blank (earlier EC01 tag, now rejected)
That last line is the bug demonstrated: a tag written earlier today under the old
scheme is unrecognised, exactly as the extension would have treated it.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
178 lines
9.1 KiB
Markdown
178 lines
9.1 KiB
Markdown
# pricegod label daemon (macOS)
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One service on `localhost:7790` that drives **both** printers over raw USB:
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| device | role | how |
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|---|---|---|
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| **Urovo D812R+** | prints TSPL labels, programs UHF chips | raw TSPL, `urovo.py` |
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| **Dymo LabelWriter 450** | prints the paper label | raw raster, `dymo.py` — **no CUPS driver, no print dialog** |
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| Chafon H-102 | reads tags off the shelf | *not this service* — see “Chafon” below |
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It is the Mac counterpart to the Windows `daemon.cs` and keeps the same HTTP contract,
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so it stays a drop-in for the PriceGod extension's `daemon.js` client.
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### Two things worth knowing up front
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**`UHF WRITE` commits immediately — it does not wait for `PRINT`.** `daemon.cs` assumed the
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encode only fired together with `printlabel`. It doesn't. That means the Urovo can program
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a chip while printing nothing, which is what makes the split flow (Urovo encodes, Dymo
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prints) possible, and it lets the daemon read the chip back to *verify* an encode before
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spending a label on it.
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**The Chafon works over serial on macOS.** ASSESSMENT.md §4 found the gun was HID-keyboard
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only on Windows. On the Mac it enumerates a CH340 bridge at `/dev/cu.usbserial-*` and the
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existing Node `rfid-daemon` speaks its protocol fine, so that dead end is Windows-specific.
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**No vendor SDK required.** `ASSESSMENT.md` §7 assumed the RFID encode was locked inside
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the Windows-only `GTSPL_SDK.dll` and would need a USB sniff or the Java jar to recover.
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It doesn't: the DLL is a managed .NET assembly, and its IL shows every RFID call is a
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one-line `String.Concat` → ASCII → `WritePrinter`. The wire format below was recovered
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from `ldstr` order + argument order and independently confirmed by a second decompile.
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```
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UHF WRITE <fmt>,<start>,<len>,<bank>,"<data>" # the RFID encode
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UHF READ <fmt>,<start>,<len>,<bank>
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UHF QUERY <fmt>,<pcStatus>,<crcStatus>
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UHF GEN2 EPC|TID|USER|ACCESS|KILL <action>,"<pw>"
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SET RFID <tagType>,<rw_pos>,<void_printout>,<tryEncode>,<errHandle>,<speed>,<retry>
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&DEFAULT,i # rfidSetupDefault &CALIBRATE,A,R # RFIDAutoCalibration
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PRINT <set>, <copy> # note the space after the comma
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```
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All plain ASCII, one command per line, CRLF-terminated. `writeUHF("H",2,12,"E",epc)`
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emits exactly `UHF WRITE H,2,12,E,"<24 hex chars>"`.
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## Setup
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```bash
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./setup.sh # brew install libusb + venv with pyusb/pillow/segno
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```
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Then double-click **`start-daemon.command`** (leave it open while you work).
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## Files
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| File | What |
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|---|---|
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| `urovo.py` | Urovo USB transport + the full GTSPL command set, status decoding, fault recovery, SKU↔EPC packing. Runs standalone as a connection test. |
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| `dymo.py` | Dymo LabelWriter 450 raster driver over raw USB. Runs standalone to report status/revision. |
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| `label.py` | Renders the label to a 1-bit bitmap with PIL, resolution-aware (203 dpi Urovo / 300 dpi Dymo). Run standalone to dump previews to `/tmp`. |
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| `daemon.py` | The `:7790` HTTP service. |
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## Routes
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| method | path | body / query | returns |
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|---|---|---|---|
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| GET | `/devices` | — | **status of Urovo, Dymo and Chafon in one call** |
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| GET | `/status` | — | Urovo only: `{ok,ready,status,statusText,printer}` |
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| POST | `/tag-and-print` | label fields + `{sku,releaseId}` | **Mode A in one call: Urovo programs the chip, Dymo prints the paper** |
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| POST | `/encode` | `{sku,releaseId}` | programs the chip at the antenna and reads it back. **Prints nothing, costs no label** |
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| POST | `/print-paper` | label fields + `size?`, `density?` | prints on the Dymo |
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| POST | `/print-encode` | `{sku,releaseId,artist?,title?,genre?,style?,info?,price?,condition?,size?,w?,h?,gap?}` | Urovo one-pass print **and** encode (needs RFID stock) |
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| POST | `/write-tag` | alias of `/print-encode` | same |
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| POST | `/print-test` | same body — Urovo prints only, no RFID (safe on chipless stock) | same |
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| GET | `/read-tag` | — | `{ok,epc,sku,releaseId,recognized}` |
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| GET | `/read-raw` | — | every memory bank |
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| GET | `/preview?size=large&artist=…` | — | **PNG of the label, printing nothing** |
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| GET | `/profiles` | — | the media profiles below |
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| POST | `/calibrate` / `/recover` | — | RFID auto-calibration / clear a latched fault |
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Use `/preview` while tuning a layout — it costs no labels.
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## Which flow to use
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- **Mode A — separate (today, existing stock).** `POST /tag-and-print`. The Urovo programs
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the chip on an RFID label; the Dymo prints the paper; you stick the paper over the chip.
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The encode is verified *before* the paper prints, so a failed write wastes nothing.
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- **Mode B — one pass (the goal).** `POST /print-encode` on direct-thermal RFID paper
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(ASSESSMENT.md §5). One label, printed and encoded together.
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## The Dymo, without a driver
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The LabelWriter 450 (`0922:0020`) is a bidirectional USB printer-class device, so the
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daemon writes its raster protocol straight to the bulk endpoint. **No DYMO driver, no CUPS
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queue, no open-window/cmd-P/cmd-W.** Command set is from DYMO's own *LabelWriter 450 Series
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Technical Reference Manual*; `dymo.py` documents each command it uses.
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Note the two printers differ in orientation: the Urovo's 24 mm web feeds narrow-edge-first
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so the design is rotated 90°, while the Dymo's 57 mm head is wider than the label so the
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same design feeds landscape and must **not** be rotated. `label.render(..., rotate=)`
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handles this, and the resolution difference (203 vs 300 dpi) comes from `profile(dpmm=)`.
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## Chafon, and the `:7790` collision
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⚠️ The existing Node daemon at `~/Documents/pliceclogs/rfid-daemon` **also listens on
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:7790**. Both cannot run at once. That daemon owns the Chafon serial protocol
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(`CF [ADDR] [CMD] [LEN] [DATA] [CRC16]` @115200) plus the postal-scale and inventory
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routes, none of which this service implements — so it is *not* a full replacement.
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Pick one of: run this on `--port 7791`; keep the Chafon daemon for the gun and run this
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one elsewhere; or fold the Chafon protocol in here. Unresolved — decide before wiring the
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extension.
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## Media profiles
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Both shop stocks sit on a **24 mm web** and feed long-edge-first, so the landscape design
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is rotated 90° onto the media. Names match the extension's size dropdown.
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| profile | label face | pitch | notes |
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|---|---|---|---|
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| `small` | 51 × 19 mm | 51 mm | older stock; the rest of the 24 mm web is blank filler, design is centred across it |
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| `large` | 55 × 24 mm | 55 mm | current stock (default) |
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| `xlarge` | 64 × 34 mm | 64 mm | untested |
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Each inherits `margin_mm` (default 1.5), a safe-area inset held back from every edge —
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without it the design runs edge-to-edge and the least registration drift clips it.
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Override per request with `size`, or `w`/`h`/`gap` directly.
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## Gotchas confirmed on macOS
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1. **`0x08` "out of ribbon" is a latch.** `SET RIBBON OFF` alone will *not* clear it — it
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also needs a `FORMFEED` (costs one blank label). `recover()` / `POST /recover` does this.
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2. **The status byte lies for 1–3 s after a print** (transient `0x20`/`0x31`/`0x45`).
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Never judge a print by the immediate post-print byte; poll until it settles to `0x00`.
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3. **`VOID0` stamps on chipless stock.** If RFID encoding is armed, every label without a
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chip gets voided. `SET RFID OFF` stops it; `/print-test` is the safe route on plain
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thermal. Note `&DEFAULT,i` appears to *arm* RFID, so don't send it casually.
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4. **Bidirectional USB is required.** `UHF READ`/`QUERY` reply with raw bytes on the
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bulk-IN endpoint, so CUPS `lp -o raw` is not sufficient — hence libusb.
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5. **After changing stock**, calibrate on the printer itself: hold **FEED** while powering
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on and wait for **5 beeps**.
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## SKU ↔ EPC scheme (✅ verified — and `daemon.cs` has it wrong)
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The shop's real scheme, matching `pliceclogs/rfid-daemon/index.js`
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(`buildEpcPayload` / `parseEpcData`), is a **single 96-bit big-endian integer**:
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```
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value = sku(14 digits) * 10^9 + releaseId
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```
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In decimal that reads as `[digits 1-14 = SKU][digits 15-23 = releaseId]`, so any scanner
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showing hex can be converted to decimal and split at digit 14. Verified against that
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file's own worked example: `20260321001001` + `35332` → `20260321001001000035332`.
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> ⚠️ **`daemon.cs` (Windows) uses a different, incompatible layout** — 6 bytes SKU +
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> 4 bytes release_id + an `0xEC01` marker. It was never checked against a real tag.
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> `parseEpcData` rejects it outright, so **any tag the Windows daemon has written is
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> invisible to the extension**. Its `Epc` class needs updating to the scheme above.
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`epc_decode` returns `None` for foreign/factory EPCs (e.g. `E28069…`), which is what
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stops a stray tag on the shelf being reported as a real product SKU.
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## Verifying a tag independently
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`chafon.py` is a read-only client for the Chafon gun over its CH340 serial bridge — an
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*independent* check that a chip the Urovo wrote holds what we think it does:
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```bash
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./venv/bin/python chafon.py # inventory the field
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```
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Confirmed working: after programming, the Chafon reads back
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`0000044A5600D4CDA1FAB932` → `sku=20260722180000, releaseId=424242`, alongside the
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untouched factory tags on the rest of the roll.
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⚠️ Only one process can hold the serial port, so don't run this while the Node
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rfid-daemon is up.
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