[mkgmap-dev] Problems with routing on Etrek 20 with latest firmware

Sat Aug 20 21:30:57 BST 2016

On Thu, Jul 28, 2016 at 08:25:32PM +0100, ael wrote:
> On Thu, Jul 28, 2016 at 10:29:07AM -0700, nwillink wrote:
> > 2) "Route calculation error"; 
> > 
> > 3) "The route does not match the available maps. Cannot follow the roads 
> > 
> > ie 
> > 
> > 1) I have previously routed from A to B using map M1
> > 2) I update my gmapsupp to map M2
> > 3) I switch on and select Recent Finds (or something like that) and click on
> > the route which I created with map M1
> > 
> > I narrowed down the problem to the fact that map M1 and M2 have different
> > map IDs and for reasons unknown but time will tell routes are linked to a
> > specific map.
> > 

I must apologise for taking so long to report back, but at least OSM has
benefited from a couple of weeks of my intensive mapping in the interim.

I now understand the problem. Firmware version 4.30 is unable to read
waypoints written by earlier firmware versions! I had discovered this
before starting this thread and found it confirmed in places like
https://yacf.co.uk/forum/index.php?topic=70084.0.

I had not encountered this sort of problem with earlier firmware
upgrades.

In passing, the old waypoints can be restored by simply passing them
through gpsbabel. Something like
gpsbabel-w -i gpx -f Waypoints_date.gpx -o gpx -F Working_WPs_date.gpx
in the Garmin/GPX/ directory fixes things. Firmware 4.30 can read
Working_WPs_date.gpx. Of course you will probably want to script that to
convert all the similar files, and remove the old ones.

When I started this thread, I had not done the conversions. So when I
invoked routing, I could not follow my usual practice with Waypoints,
so used "recent finds". As nwillink (thanks again) pointed out, it seems
that these Recent finds do not use simple coordinates, but cache at
least some elements of the map when they were last used. Which then
fails if the map has been subsequently changed. Which seems like buggy
Garmin firmware. 

I am still surprised not to have come across this problem before, given
that I am pretty confident that I have used "Recent finds" even when 
Waypoints were available, and that I regularly update the map. So
perhaps this is a new problem with firmware 4.30.

I have included a fair bit of detail in case others have problems after 
the firmware upgrade and find this thread.

I am not sure that I recommend 4.30. It seems to take much longer to
start up than the earlier firmwares. 

Thanks again for all the replies and help.

ael