Update procedure for ZLog-7 Rev2 GPS module firmware.
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NOTE: this is for the ZLog-7 Rev2 units only.  Rev1 hardware has a different GPS
module and does not use this update.

Items required:
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- USB mini-B cable (PC to ZLog-7)

- ZLog-7 Rev2
    - requires Z7 firmware version 2.21 or greater for GPS update 
      capability.  See Appendix A of the manual:
         http://www.hexpertsystems.com/zlog/Z7/Z7-2-Manual-8.pdf
      The Z7 Loader and firmware can be downloaded from the web page:
         http://www.hexpertsystems.com/downloads.html

- GPS update zip file "Z7-GPS-Update-5759.zip"

Setup:
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- ZLog-7 Rev2 with Power jumper J2 in the "USB" position.
- Decompress the zip file to a temporary directory on your PC.

Update Process:
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1) Plug in the USB cable to the ZLog-7.
2) Press and hold button S2 on the ZLog-7.
3) Plug in the USB cable to the PC.
4) Continue holding button S2 until the ZLog-7 display reads "GPS BRDG".
   This is a pass-through mode that allows the PC to talk directly to the GPS.
5) Go to the directory containing the unzipped GPS update files.
6) Run the "PowerFlash.exe" program.
7) Click the "Download Agent" button.  Verify that MTK_AllInOne_DA_MT3339_E3.bin is selected.
8) Click the "ROM" button.  Choose file AXN2.31_5759_3339_96.1151100.1.bin.  This is the new firmware for the GPS.  Select "Open".
9) Click the "ComPort" menu and "COM" and choose the port for the ZLog-7.  
10) Click the "ComPort" menu and "Update Baud" and choose "9600".
11) Click the "Connect" button.

12) Click the "Download" button.
    - first the download agent (red bar) will load.  This takes about 20 seconds.
    - second the new firmware (blue bar) will load.  This takes about 10 minutes.

13) Once the update has completed, close the PowerFlash program.
14) Unplug the USB cable from PC and ZLog-7.
15) Move the Power Jumper J2 back to the "BAT" position.
16) At powerup, ZLog-7 will record the new GPS version in the Z7-LOG.txt file 
    on the microSD card.  You can verify the new version by looking at the last
    entry in the file.