GPS Date wrong by 20 years

[AFK88L]

I recently noticed an issue with my C127 dash display showing the wrong date.

I believe I've worked out the root cause (and a workaround), but just wondering if a firmware update is possible that could fix this issue?

It's been working correctly for years, but some time in the past 6-12 months (hadn't been paying that much attention) the date started to display incorrectly.

Setup is a C127 Race Display Kit that I purchased back in Aug 2016. This came with a 10Hz GPS unit (L10).

I've been using my own custom Display Creator design, with no changes since 2021, and it had always been correct until now. I output the DOW Day/Month and Time (24hr) to the bottom section of the display, as below.



This was taken on "Tue 28/04" but the display was showing "Tue 12/09".

Thinking a Display Creator issue, the next day I updated the display to output the full date (also upgraded to Dash Manager 6.51.12.0 and Display Creator 6.5.1.0205 at the same time to see if there was a fix already).



So the full date showed as 13/09/2006 instead of 29/04/2026.

I finally realised I should actually monitor the GPS Date channel value and found that's where the issue is. The GPS unit is outputting the wrong date?



It was outputting a value of 130906 (DDMMYY).

I noticed something when I did a date calc between the two dates.



1024 weeks looked suspect.

I have since learned GPS systems use a week count plus time-of-week value, since a certain date.

So it looks like my L10 GPS device might only be using a 10-bit value for the weeks (max value 1023) which means there's a date rollover issue every 1024 weeks (since some internal hardcoded start date), I think?

My workaround has been to create a constant channel with a value of 7168 and use this as the "Date Offset (Days)" in the Real Time Clock config of Dash Manager.

That works, but wondering if a firmware update is possible to ensure the GPS Date channel value is correct in the first place?

[Stephen Dean]

Hi,

Try this resolution.

[AFK88L]

Hi Stephen,

Thanks for pointing out the support article.

I see from this I can return the L10 unit to get it flashed. Was hopeful for an in place software update as my C127 has been integrated into the cars dash and the L10 unit is quite a hassle to remove. No worries, I'll leave it for another time if I'm ever pulling the dash apart again.

Also curiously I purchased this in 2016 (before the affected units sale dates you listed of 2019 to Aug 2025).

BTW, I'm only using Dash Manager and Display Creator to show the date (not i2), so I don't think I can use the workaround in the article? Also, the screenshot shows offsetting the "GPS Time" channel, which confused me at first - shouldn't it be the "GPS Date" channel?

Unless there is a better way, I'll have to stick with my Dash Manager fix which appears to be working for now (add 7168 days as a GPS Date offset to the Real Time Clock). Thanks.