continuing from part 1 where the technological progress over the last 20 years from a handheld, dedicated GPS receiver to the ubiquitous GNSS chip that’s in all modern smartphones was discussed:
Back in the early 2000s I used to use the GPS 315 to provide location to my Psion Series 5 running “En Route” – in many ways this hardware & software combination was a precursor to Tom Tom satnav receivers. I made up a dedicated RS232/power lead to connect the Magellan & Psion together and provide power to them both. I recently re-discovered the lead in the bottom of a desk drawer… it’s not aged well 😀
I last powered up the GPS 315 in the summer of 2020 and it was still showing the correct date, but when I powered it up again just before writing this post in Jun 2021 it looks like it’s suffering from the dreaded GPS week number rollover problem. Although the GPS system has absolute dates when the “Week Number Roll Over” (WNRO) happens lots of receiver manufacturers have written their firmware to start counting weeks from whenever the code was compiled. Despite resetting the memory and initialising my Magellan unit with the present date in 2021 it still likes to go back to 1024 weeks ago – late October 2001 at the time of writing 😀 My unit is running firmware version 3.14 which was released 08/05/2001 so I reckon it rolled-over around the end of December 2020. The last firmware version (v3.15) released for this unit was 26/02/2002 – 1024 weeks after that is 12/10/2021 – so if I can upgrade it before then I might have a few months of correct date again 😀 It would be interesting to see what the unit does during the week rollover…
And just to be clear – the wrong date does not affect any of the location functions at all, the unit still works perfectly as a navigation aid.
I managed to upgrade the unit to v3.15 – but that required finding an old laptop running XP that had an actual 16550-compatible hardware UART serial port (not USB/serial adapter!) (Running XP or Windows 10 in a VM with USB/serial adapters didn’t work at all – the Magellan upgrade software couldn’t detect the presence of the unit)
Unfortunately v3.15 still shows the incorrect (1024 weeks ago) date. Poking around in the firmware binary with tools like binwalk & strings it looks like both v3.14 and v3.15 are hard-coded with the same date 17/04/2001 – this corresponds to the date/timestamp on the actual NXS_315.bin file (I found 48 6d dc 3a = 3adc6d48 = GMT: Tuesday, April 17, 2001 4:20:24 PM at offset 0x0074013 in the v3.14 file and offset 0x0074015 in the v3.15 file). Other things of interest are:
[cxf]$ binwalk -B NXS_315.bin
16792 0x4198 Copyright string: "Copyright 2001 Thales Navigation, All Rights Reserved"
18905 0x49D9 Copyright string: "Copyright (c) 1990-1992 KADAK Products Ltd."
[cxf]$ binwalk -A NXS_315.bin
24758 0x60B6 Motorola Coldfire instructions, function prologue/epilogue
24866 0x6122 Motorola Coldfire instructions, function prologue/epilogue
24894 0x613E Motorola Coldfire instructions, function prologue/epilogue
24922 0x615A Motorola Coldfire instructions, function prologue/epilogue
25018 0x61BA Motorola Coldfire instructions, function prologue/epilogue
In between the v3.14 and v3.15 release the Magellan company had been acquired by Thales Group, hence the copyright message. The “strings” command also finds:
“AMX 68000 (TM) v2.06 All rights reserved.“
It looks like the Magellan unit runs the Kadak AMX RTOS v2.06 on a Motorola Coldfire (68000 derivative).
Looking for support and/or updated firmware I found the following useful resources:
Review of the GPS 315 from 1999 vs. the Garmin 12XL here
Magellan press release when GPS 315/320 were released here
Magellan GPS 315/320 manual here
List of Magellan firmware updates here
Firmware update v3.15 for GPS 315 or 320 models available here
or download directly below:
A laptop with a real 16550-compatible hardware UART serial port!
Back to Part 1: https://zedstarr.com/2021/06/08/magellan-gps315-vs-the-future/
Room 7609 
It’s decades since I wrote a program but…
If the displayed date on an affected ‘old’ GPS is always exactly 1024 weeks prior to the correct current date, how about editing the program code such that 1024 is added to the GPS-transmitted Binary Week Number? When the software then converts this adapted Binary Week Number the output date (in human format) will be correct.
Yep – exactly. If the exact location where the week-number maths is done is known (in the binary program code) it could probably be patched. To change the source and re-compile you’d have to have access to the original source code (which I’m guessing Magellan/Thales kept proprietary & private) and the toolchain to compile/build the code.
Hi
I hope this finds you as you seem to be the only person who knows how to fix the Magellan 315 roll-over problem!
My 315 does every thing except find the satellites, I have not used it for a couple of years as I was in the process of moving to Australia, it did initially find them but it has failed to since.
I cannot find a v3.15 firmware up date anywhere, I still have an XP computer though. Are you able to supply a copy so I can try and up date it. I use the 315 to work the auto pilot and the yeoman chart plotter on my trailer sailor which I shipped out to OZ. I am in my mid 70,s so like to stick with what I know works.
Any help much appreciated
Ian
There’s a big green download button for the GPS315.ZIP file on the page above ^^^
(or failing that there’s a download link to the internet archive in the line above the download button 😉 )