I got the soldering iron out again this week... These are the places to solder to if you want to "play" with a GPS device:
How they plug in:
WARNING! Vaguely tested - may cause much grief!
How to install navigation software on a USB stick for use on a mid level FG MKII FDIM: (requires debug port access on two units)
Gather the software from a donor FGII nav unit (you didn't think this would be easy, did you?!). Also take a copy of your existing /packages/factory/manifest.packages file. Merge the content folders from the donor units navi and navi_maps packages, copy over the license folder too. These should all go into a directory called root/usr/navngo/MobileNavigator on the USB stick matching the same directory structure as the units. Create a navi folder on the stick too, put a copy of the /packages/factory/navi/info and /packages/factory/navi/scripts folders in that - so you have navi/info & navi/scripts on the USB stick.
Add the navi entry to the end of your existing /packages/factory/manifest.packages file: (put it on the USB stick to edit and "cp" back it into place later):
<file content>
applications 336692
...
swsa_binaries_and_libraries 330391
navi 342767
<end file content>
The last line is what needs to be added to your existing manifest file. It's important not to use the nav unit's file because if you are missing anything listed then your unit will not fire up correctly.
These are the /packages/factory/navi/root/usr/navngo/MobileNavigator/sys.txt changes needed (navi start settings). These changes are mostly to fix up the missing tmc device, but also I send the save data into a RAMDISK (this means a power interruption will wipe your settings, but also, we won't fill up what precious little space is available in the flash memory on these small "mid" FDIM units = 128MB).
Newer (2014) units have a segments setting which I would turn off (=0), and I added the no_tmc=1 debug setting too - but this isn't the important area to change:
[debug]
enable_tmc_segments=0
no_tmc=1
Folder section for where to save data:
[folders]
;data="/fs/etfs/packages/persist/NNG_save" <--- This is the original save path
;data="/fs/ram/NNG_save" <--- you will see this in the existing file, I don't think it can be used as ram isn't a file system on the device.
data="/fs/tmpfs/NNG_save"
Add this tmc section to stop the traffic radio from being used, without these settings, when the unit goes to sleep it will timeout trying to shut down the missing radio, effectively crashing the software and it will need a restart:
[tmc]
show_tmc=0
init_on_startup=0
reinit_on_hardware_lost=0
ignore_suspend=1
ignore_resume=1
override_saved_config=1
I think it's important not to use the flash memory space because that will limit the system's ability to relocate bad-blocks of data in the left over block pool. In fact, I have removed two themes (replaced them with a symbolic link to "borderless" which is my choice of themes to keep) to free up 42MB of space for R&D and bad blocks.
Create the navi directory on the unit with just the info & scripts folders copied over (previously put on the USB stick):
cd /packages/factory
cp -LR /fs/usb0/navi .
Create a symbolic link for the navi "root" directory, pointing it to the USB stick:
cd /packages/factory/navi
ln -s /fs/usb0/root root
Create the required sym links that the unit needs to run packages:
cd /etfsRoot/bin
ln -s /packages/factory/navi/root/bin/gps gps
ln -s /packages/factory/navi/root/bin/navi_2_hmi_connector navi_2_hmi_connector
cd /etfsRoot/info
ln -s /packages/factory/navi/info navi
cd /etfsRoot/scripts
ln -s /packages/factory/navi/scripts navi
cd /etfsRoot/usr
ln -s /packages/factory/navi/root/usr/navngo navngo
As a last step, as, if this is wrong your unit will complain and stop very early on in a boot.. use these commands copy the manifest and keep a backup!:
cd /packages/factory
mv manifest.packages manifest.packages_o
cp /fs/usb0/manifest.packages .
Restart the unit with the USB stick inserted (if it isn't inserted, it will revert a normal mid level FDIM until it's rebooted again). You can unplug the USB stick, the navi software will pause until it can re-open the files, though to be safe I'd only do it while the nav software isn't showing. If you update the maps which are now stored on the USB stick, make sure you reset the unit (whatever method you prefer - battery disconnect, Forscan, or my favorite: the debug port "shutdown" command). I've also used both the older and newer navi software that I have on an older unit and both worked the same. I.E. no aparent incompatibilities.
You can clean up the USB stick so it only has a "root" directory now. Maybe copy some mp3s onto it (though the more there are, the slower it'll take to boot because of competing accesses).