[time-nuts] BC637PCI 1024 week rollover
GandalfG8 at aol.com
GandalfG8 at aol.com
Sun Feb 9 16:23:27 EST 2014
It may be that your onboard batteries are in better health than mine are,
although mine might have been disabled using the software, as I tried
booting up without an antenna this evening and got the right year this time but
twith he date as 1st January:-)
What I found when running in GPS mode was that I could correct the date but
it would get overwritten again.
As I commented in my previous reply to Magnus' comments, I still don't
understand why units produced after 1999 should have this problem anyway.
Thanks for the data, I'll keep that and compare later, and I'll be very
interested to hear how yours performs once the antennna is connected.
Running off 1PPS is an option but I'd much prefer to use actual GPS time if
possible, unfortunately, as commented earlier, the problem lies with the
BC637 itself, not the GPS module.
Your mention of other GPS modules reminds me that the appropriate set of
schematics for these BC637s shows that a header swap would allow the board to
use a Motorola Oncore in place of the Trimble ACE2 or ACE3. Not sure that
I'll ever try that but it might help explain why they take the raw GPS
data rather than what's already been processed by the module.
In a message dated 09/02/2014 15:34:22 GMT Standard Time, time at patoka.org
I'll be glad to check my GPS module to see what is going on there,
however I am still waiting for the GPS antenna to be delivered. I tried
to use some small form factor Trimple GPS antenna with BC637, but
on-board GPS module couldn't lock with it. So, my BC637 is working in
"freerun" mode now:
Mode : Free Run
Time Format : Binary
Year : 2014
Local Offset : 0.0
Propagation Delay : 0
Current Leap Seconds : 0
Scheduled Leap Event Time : 1391731200
Scheduled Leap Event Flag : Insertion
GPS Time Format : UTC Format
IEEE Daylight Savings Flag : Enable
I have no issues with date stamp in that mode:
Binary Time: 02/09/2014 14:36:19.7005289 Status: 0
Binary Time: 02/09/2014 14:36:19.7105941 Status: 0
Binary Time: 02/09/2014 14:36:19.7206589 Status: 0
Even if I switch BC637 to "GPS mode, it still using correct date. Which
is expected, because in accordance with documents, if GPS is not locked,
BC637 will behave in the same way as "free run". The difference is the
Status. Its shows, four bits. And one of them indicates that GPS is not
Binary Time: 02/09/2014 14:37:43.0045326 Status: 7
Binary Time: 02/09/2014 14:37:43.0146051 Status: 7
Binary Time: 02/09/2014 14:37:43.0246776 Status: 7
As soon as I'll get my "bullet GPS antena" attached, I'll see what is
going on there for the date stamp. Also, in the documents, I saw some
sections, which explain how to use data registers to send some command
to Trimble GPS. Probably its is possible to do some corrections through
May be it is possible to attach another GPS module to the BC637 card.
Its using 9 pin connector.
This connector is used primarily for connecting the ACE III GPS. Data
between the board and the GPS receiver are via serial signals.
Additionally, the GPS receiver
provides a 1 PPS signal to the board.
On 2014-02-09 06:56, GandalfG8 at aol.com wrote:
> Oh well, full credit to Mr Trimble for getting it right, he does bake
> exceedingly nice GPS modules and the Ace3 doesn't have a rollover issue
> and it
> does report the date correctly.
> Unfortunately, as far as I can tell anyway, the BC637PCI takes the raw
> time data from the Ace3 and performs its own calculation which is where
> problem seems to occur, certainly it's a 1024 week issue with the date
> from the BC637 being displayed as June 26 1994 in all versions of the
> associated demo software.
> It is possible to set the date correctly but the next packet from the
> module promptly overwrites it again.
> I still don't recall seeing this before, although with two boards
> in the same fashion I'm having doubts about that, but more to the point
> these boards indicate a firmware date of 2003 which implies they were
> into the field like this, and that doesn't make much sense either.
> Any ideas anyone?, and again has anyone else seen this and/or am I
> something glaringly obvious?
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