REgarding TomTom. I managed to install it and get it working. The problem is well known for KitKat, and is what you actually mention. KitKat has some extra security measures and does not allow non-primary apps to write on external SD cards. That is why in principle you need TomTom 1.3.2, which was supposed to overcome that. If you install it and you keep the maps of the previous version (3.96Gb in Europe...) it does not find them. The reason is that Tomtom 1.3.2 is looking for the maps on the internal sd card and not in the folder "tomtom/com.tomtom.europe/" but in "Android/data/com.tomtom.europe/". So, here is the problem. There is no 4Gb in the internal memory. But, I found a "partial" workaround.
How to install tomtom
1- clear any previous version you had in the headunitThis works. But I found a problem.
2- install tomtom 1.3.2 but do not run it, it won't find the maps
3- create the following folders in your internal sdcard "/Android/data/com.tomtom.europe/files/files"
* instead of "europe" you must use your own maps
4- copy the file ".metada.xml" that you have on your GPS card under "tomtom/com.tomtom.europe/.metadata.xml" to the folder "/Android/data/com.tomtom.europe/files"
5- open this file and modify the path that you find there to: "/mnt/internal_sd/Android/data/com.tomtom.europe/"
At this point you have the right file structure, but there are no files in the internal sd card.
You cannot copy all the maps there because there is no space. The solution is to create a link.
6- Download folderMount from play store
7- Create a link from /mnt/internal_sd/Android/data/com.tomtom.europe/files/files/ --> "/mnt/external_sd/tomtom/com.tomtom.europe/files/" (or wherever you have your maps in the GPS card)
8- "run the link, it is the pin icon. WHen created, you will see a green pin next to the link
9- run tomtom
Tomtom is running and you turn off the car and the unit. When you restart, tomtom starts before the link is created, so it starts and finds no maps. After a little while the link is created, and then you can see the maps again but the settings, address, and everything that you set up earlier is gone. So, I guess tomtom is not writing the settings or because they are written on the folder that is linked, it does not find them and restarts as fresh.
The solution is to create the link before tomtom runs. Best option would be inputing the link code before anything is running. I do not know how it can be done, but I am sure it can. It is just an easy linux command.
- create a link between internal_sd card and external_sd at boot before any app is workingWARNING:
- fix settings writing.
If you uninstall the application when the link is on, it will erase the maps on your GPS card.
Hope it helped.