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[SOLVED] Cheap unbranded USB GPS dongle from China
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daniel.santos
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Joined: 05 Jun 2007
Posts: 27

PostPosted: Wed Mar 27, 2013 5:16 pm    Post subject: [SOLVED] Cheap unbranded USB GPS dongle from China Reply with quote

I love scary titles! So I think (hope?) most people have done this before, found some nice (looking) accessory and brought it before checking to make sure there was a Linux driver. Well this time, it was only $25 so the damage wasn't that bad, but once I had already paid for it I was determined to reverse engineer the damn thing and redeem myself!

So this came from ankaka.com and was described as a GPS USB Receiver for PC/Laptops (Fast Sync with 65 Channels and Compatible with most brands of GPS software). I stuck it in and did lsusb
Code:
Bus 004 Device 006: ID 10c4:ea60 Cygnal Integrated Products, Inc. CP210x UART Bridge / myAVR mySmartUSB light

Fuck! They didn't even bother programming the USB interface's PROM! Now that's CHEAP! It's one thing if they don't change the Vendor ID & Product ID since it costs $3500 to get a Vendor ID from the USB Forum, but they could at least change the description, it's just a goddam USB command! (Well, you have to ground a PIN as well.)

So this USB interface is the CP2104 USB to UART Bridge Controller (originally by Cygnal Integrated Products, but since acquired by Silicon Labs) and this interface is (luckily) pretty straight forward. I can't find real data on the GPS chip, it is apparently now obsolete, but appears to be a cousin or predecessor to this "GPS module with antenna SKM53" (which says "G229" on the top and not "SKM53") by the Chinese company Skylab (a.k.a. Skylab Technology Co., Ltd., a.k.a Skylab M&C Technology Co., Ltd.). However, the chip in this dongle says "G233" on top and I have no idea what the original part number really was.

So the good news is that it will work out of the box with the in-tree driver cp210x (CONFIG_USB_SERIAL_CP210X), which you can enable via "Device Drivers --> USB Support --> USB Serial Converter support --> USB CP210x family of UART Bridge Controllers" in menuconfig. Load that module up, cat /dev/ttyUSB0 and get your GPS spew!

EDIT: Oh yeah, this spew is apparently the NMEA-0183 protocol.

Code:
Bus 004 Device 006: ID 10c4:ea60 Cygnal Integrated Products, Inc. CP210x UART Bridge / myAVR mySmartUSB light
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  idVendor           0x10c4 Cygnal Integrated Products, Inc.
  idProduct          0xea60 CP210x UART Bridge / myAVR mySmartUSB light
  bcdDevice            1.00
  iManufacturer           1 Silicon Labs
  iProduct                2 CP2104 USB to UART Bridge Controller
  iSerial                 3 005DD8B2
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           32
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0
      bInterfaceProtocol      0
      iInterface              2 CP2104 USB to UART Bridge Controller
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
Device Status:     0x0000
  (Bus Powered)
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jpc22
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Joined: 29 Jan 2012
Posts: 186

PostPosted: Wed Mar 27, 2013 7:27 pm    Post subject: Reply with quote

Could you tell me how good is the signal with that device and does it compares to a regular gps?
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daniel.santos
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PostPosted: Thu Mar 28, 2013 2:12 am    Post subject: Reply with quote

jpc22 wrote:
Could you tell me how good is the signal with that device and does it compares to a regular gps?

Sorry, I can't really say yet, although it does get a signal from inside my house a few feet away from a window. That's better than my garmin will do sometimes, but I can't really rate the product its self just yet. I brought it for part of a hack-together telescope drive system and it works well enough for that, so I'm done testing for my purposes. :) I suppose I could hook it up to my laptop and ride around with my fiancé one day and compare it to the garmin nuvi, but I'm not making any promises.
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jpc22
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PostPosted: Fri Mar 29, 2013 5:35 pm    Post subject: Reply with quote

Seems good for the price.

By telescope drive system do you mean you have a telescope strapped to a rc car, or someting that drives a telescope around?
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