Working with GPS Units


in this lesson

CalTopo uses standard formatting for map objects, such as lines and markers. These can be moved to and from your GPS device with import and export. The CalTopo part of this process is well described in the Import and Export Functions Chapter. If you need additional help working with your GPS device, the instructions below should be of aid.

Additionally, users with a Pro subscriptions or higher can use some CalTopo baselayers and the map display in some Garmin devices. Those instructions are in the second section below.

Topics on this Page:

Moving Data between your GPS Unit and CalTopo

You can import and export data using a couple of methods.

  1. (Most Common) Access GPS Units that support a USB Mass Storage Interface through the file interface.

    USB mass storage interface means that when you plug the GPS into your computer, it appears as a USB drive, like a thumb drive or external hard drive. All new GPS devices and most devices currently in use utilize mass storage. A list of Garmin GPS units that support a USB mass storage interface can be found here.

    In addition the Garmin GPSMAP 60CSx can be accessed as a USB storage device with a little work- check out this article.

  2. (Very Old Garmin Devices) Connect directly to a Garmin GPS using GPSIO

    GPSIO is a still-experimental replacement for the Garmin Communicator plugin, built on open web standards and using GPSBabel to read GPS data. Additional information is available here. See below for installation instructions.

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USB Mass Storage Interface Method

These instructions assume a Garmin GPS, but similar steps will work with other GPS units that support a USB mass storage interface.

Connect the GPS to the computer with a USB cable. It may take the GPS a minute or two to save the tracks and establish a connection. Once the connection is established, the computer may chime and/or a file explorer window will open for the GPS in Windows. On a Mac, a Garmin folder will appear on the desktop.

Importing GPS Tracks and Waypoints as Lines and Markers using the USB Mass Storage Interface Method

  1. On the CalTopo top menu bar, click "Import" and "Choose Files".

  2. Navigate to the Garmin unit, and then the Garmin / GPX folder, select the desired track and/or markers and click "Open".

  3. Un-check any waypoints or tracks you do not want to import and click "Import".

  4. Track will appear in the "Lines & Polygons" folder, waypoints will appear in the "Markers" folder.

Exporting Lines, Polygons and Markers to GPS Units using the USB Mass Storage Interface Method

  1. On the CalTopo top menu bar, click "Export" and "Download GPX File".

  2. Un-check any objects you do not want to import and click "Export".

Depending on your browser and how it is configured, you may be prompted where to save the file or it may be automatically saved in your downloads folder.

If you are prompted where to save the file:

  1. Navigate to the Garmin unit, and then the Garmin / GPX folder, change the file name as desired and click "Save".

If the file was automatically saved in your "Downloads" folder:

  1. In the bottom bar of the browser (the example shown is Chrome) click the menu beside the file and choose "Show in Folder" .

  2. Now drag the file to the Garmin\GPX folder on the GPS Unit.

Ejecting a GPS Connected Via USB

In Windows, eject the GPS by clicking on the USB icon in the System Tray and then selecting the Garmin unit.

In MacOS, eject the GPS by right-clicking on the GARMIN folder on the desktop and click "Eject "GARMIN".

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GPSIO

Installing the GPSIO Extension

For the time being, GPSIO installation is a multi-step process that requires a bit of computer savvy. Hopefully, at some point in the future, this will all get boiled down to a single-click install.

Install the prerequisites if not already installed on your computer:

  1. Python, which comes pre-installed on Mac and Linux installations, but may need to be installed for Windows. Click here to download the latest Python for windows. During installation, make sure to enable the option to "Add Python to environment variables" (or similar wording) so that other programs can make use of it. If needed, you can run the install program again, and modify your existing Python installation, to enable that option.

  2. GPSBabel, an open source program for working with GPSs and GPS data (consider making a donation). Click here to download.

  3. For Windows: the latest Garmin USB drivers, available here. For USB-mode devices (Garmin 60 or similar non-mass-storage-mode devices), you can run Windows Device Manager to verify the driver installation: if the drivers are installed properly, a plugged-in Garmin USB-mode device will show up in a category named "Garmin Devices"; if the drivers are not installed, a plugged-in Garmin USB-mode device will show up as "Unknown USB Device", causing CalTopo GPSIO transfers to abort with a red line of text indicating that no GPS was found. (Mass-storage-mode devices such as Garmin 62, 64, etc. will instead show up under 'Drives' and/or 'Portable Devices'.)

To comply with browser security restrictions, GPSIO is composed of two parts: an extension and a host. You need to install both parts.

  • Install the host. Download. On windows systems you must unzip this file by right-clicking on it and choosing "Extract All"; the installer will not work properly if you navigate into the zipped folder by double-clicking on it in the windows file explorer. Either double-click on the install.py script or open up a command prompt and run "python installer.py".

  • Install the extension in your browser.

Importing GPS Tracks and Waypoints as Lines and Markers using GPSIO

  1. Connect the GPS to the computer with a USB cable. It may take the GPS a minute or two to save the tracks and establish a connection.

  2. On the CalTopo top menu bar, click "Import" and "Connect via GPSIO".

  3. A message will appear while the GPS is being read.

  4. If the connection is unsuccessful, you may see an error message. The extension may not be correctly installed, or you may have not given the GPS long enough to connect.

  5. A second message will appear once the data has been read and is being processed.

  6. Un-check any waypoints or tracks you do not want to import and click "Import".

  7. Track will appear in the "Lines & Polygons" folder, waypoints will appear in the "Markers" folder.

Exporting Lines, Polygons and Markers to GPS Units using GPSIO

  1. Connect the GPS to the computer with a USB cable. It may take the GPS a minute or two to save the tracks and establish a connection.

  2. On the CalTopo top menu bar, click "Export" and "Connect via GPSIO".

  3. Un-check any objects you do not want to import and click "Export".

  4. Once the export is complete, you will see this message:

  5. If the connection is unsuccessful, you may see an error message. The extension may not be correctly installed, or you may have not given the GPS long enough to connect.

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Birds Eye Format Maps for Garmin Devices

Pro-level subscribers can preload CalTopo's high quality map layers onto their GPS and be prepared wherever they go. These JNX formatted maps are compatible with Garmin GPSs that support BirdsEye(TM) imagery, such as the 62s, 64s, and most touchscreen models. However, you must unlock your GPS so that it will work with 3rd party maps not sanctioned by Garmin.

Because the JNX format does not support transparency, maps come in several pre-set combinations:

Coverage for named JNX files can be located on these maps: USGS / Slope Angle Shading and Aerial Imagery. Some newer files dropped the named-area convention in favor of having each file cover a 1 degree by 1 degree grid. These are named based on the southeast corner; 42x111 covers everything between 42 and 43 degrees of latitude, and 111 to 112 degrees of longitude.

To get started, just go to the downloads tab on your account dialog, and then click on a specific link.

Example of each object on gray background.

GPS Download area in Your Account

Some sample screenshots:

Unlocking your GPS Unit

Garmin GPSs will display vector (point and lines, ie gpx files) maps from any source. However, they are locked to only display official, Garmin provided raster (image) maps. Unfortunately there isn't an approval process for 3rd party map providers like CalTopo - so there's no way for me to provide JNX maps that will work out-of-the-box. In order to use CalTopo's downloadable JNX maps, you need to unlock your GPS to work with all JNX files regardless of origin. Obviously this is not something supported or approved by Garmin.

To unlock a GPS, you need to:

  1. Download the latest firmware for it.
  2. Download a firmware patcher.
  3. Patch the firmware to create an "unlocked" version.
  4. Install the new, unlocked firmware onto your GPS.

Both the patcher and links to the latest firmware versions are available from http://whiter.brinkster.net/en/Versions.shtml. The patcher is a windows-only program; start it, select the file you want to patch, and it will create a new copy with "patched" in the name.

To install a new firmware file, first make sure you have good GPS batteries. Then rename the file to GUPDATE.GCD and copy it to the Garmin folder on your GPS. It should now be located at [GPS Drive Letter]:\Garmin\GUPDATE.GCD. Unplug the GPS, turn it on and you should see a "verifying firmware" message or similar.

Please note that I am a map provider only. Unlocking your GPS is risky, and you alone assume that risk. I am not associated with the firmware patcher and have no responsibility for or control over it. I cannot provide tech support for its use - you are responsible for figuring out how to patch and install firmware.

Unsure? You can download a sample map and take it for a test drive. With locked firmware, you will see an "Invalid JNX File" error message on startup. With unlocked firmware, you'll have aerial imagery between 44 N, -117 W and 46 N, -116 W.

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