add usbprinter device_id string

.gitignore

@@ -4,3 +4,4 @@ __pycache__
 *.egg-info
 *.bak2
 .venv
+dymott

README.md

@@ -48,6 +48,16 @@ print(f"Dymo 450 string result as bytes: {usb.control.get_descriptor(dymott,254,
 The Twin-Turbo serial is supposed to be 006103010161575. Due to the extra 0 byte `b'\x30'`, the rest of the return data becomes shifted and is interpreted like
 `b'\x30\x30\x00\x36\x00\x31\x00\x30\x00\x33\x00\x30\x00\x31\x00\x30\x00\x31\x00\x36\x00\x31\x00\x35\x00\x37\x00\x35'.decode('utf-16-le')` or literally unicode values `\x3500\x3700\x3500\x3100\x3600\x3100\x3000\x3100\x3000\x3300\x3000\x3100\x3600\x3030`
 
+Dymo 450 GET_DEVICE_ID example string:
+```
+'MFG:DYMO;CMD: ;MDL:LabelWriter 450;CLASS:PRINTER;DESCRIPTION:DYMO LabelWriter 450;SERN:01010112345600;'
+```
+
+Dymo Twin Turbo GET_DEVICE_ID example string (note the null byte before ERN:):
+```
+'MFG:DYMO;CMD: ;MDL:LabelWriter Twin Turbo;CLASS:PRINTER;DESCRIPTION:DYMO LabelWriter Twin Turbo;\x00ERN:006103010161575'
+```
+
 Note: Linux Mint 22.1 <- Ubuntu 24.04 Noble <- Debian Trixie/sid <- Kernel 6.8.0-71-generic; pyusb version 1.3.1; python version 3.12.3
 
 References
@@ -66,3 +76,5 @@ https://kernel.org/category/faq.html
 
 https://bugzilla.kernel.org/show_bug.cgi?id=220422
 
+https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/LegacyCollaterals/01233a.pdf
+

src/dymott.py

@@ -38,6 +38,19 @@ dymo_450_serialdata = usb.control.get_descriptor(dymo_450, 30, 0x03, 0x03, 1033)
 def get_serial_raw(dev):
     return usb.control.get_descriptor(dev, 254, usb.DT_STRING, dev.iSerialNumber, dev.langids[0])
 
+def get_device_id(dev):
+    # Get the IEEE 1284 Device ID string
+    # ref: https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/LegacyCollaterals/01233a.pdf
+    GET_DEVICE_ID = 0xa1   # USBPRINTER protocol bmRequestType printer protocol request
+    bRequest = 0x00        # USBPRINTER protocol bRequest get_device_id
+    GET_PORT_STATUS = 0x01 # USBPRINTER protocol bRequest get_port_status (returns 1 byte)
+    SOFT_RESET = 0x21      # USBPRINTER protocol bmRequestType soft reset
+    wValue = 0             # USBPRINTER protocol Config Index
+    wIndex = 0             # USBPRINTER protocol interface index and alt setting
+    wLength = 1023         # Max buffer length
+    # ctrl_transfer(bmRequestType, bRequest, wValue, wIndex, msg or buffsize)
+    return dev.ctrl_transfer(GET_DEVICE_ID, bRequest, wValue, wIndex, wLength)
+
 def get_serial(dev):
     rawserial = get_serial_raw(dev)
     # Return just the data portion of the descriptor data
@@ -67,7 +80,8 @@ def fix_serial(uri_line):
         # CUPS output looks like:
         # direct usb://DYMO/... "DYMO LabelWriter Twin Turbo" usb://...
         # We'll add a stable dummy fallback here
-        dummy_serial = "DYMOFIX-" + str(abs(hash(uri_line)) % 10000)
+        #dummy_serial = "DYMOFIX-" + str(abs(hash(uri_line)) % 10000)
+        new_serial = get_serial()
         uri_line = uri_line.replace(f"serial={serial}", f"serial={dummy_serial}")
 
     return uri_line