[time-nuts] TruePosition GPS Receiver

Ben Hall kd5byb at gmail.com
Tue May 9 19:02:23 EDT 2017

Good evening Paul and list,

So I've been working on the LMU300 tonight.

On 5/6/2017 8:13 PM, ziggy9+time-nuts at pumpkinbrook.com wrote:
> A couple of observations on the LMU300:
> - the console port is the AEP port, a 6 pin RJ-11 - and you need a 6 pin connector
> - the USB port is non-functional

I decided to verify that the USB was non-functional...just in case your 
unit had an issue.  Wow I wish I had not!  Win7 started to install a 
driver, failed to install, then got BSOD.  Reboot...and immediate BSOD. 
After about an hour of troubleshooting I determined that somehow, and I 
don't know how this could happen, it corrupted the driver of my Prolific 
USB-to-Serial converter...as I determined that BSOD only happened when 
it was plugged in.  Had to flush out the driver and reload...and now all 
is well again.

My LMU300's GPS never gets past the boot screen...but somehow...the GPS 
light goes green?  That GPS light must not really be looking at the 
GPS...or its more akin to a "GPS board seems present" versus "GPS is 
working, seeing satellites, etc..."

>      - pin 5 or the third pin in the row closest to U19 is the 12v input (measured). the other 4 are all ground.

Mine is 12VDC as well - right on the money too.  I thought 15 VDC was 
odd - the unit has 12VDC fans...why not have one 12 VDC supply and run 
both the fans and GPS unit from it?

> - the 15 pin header:
>      - pins 7 and 8 are 3.3v ttl level, and contain the same data as J2 pin 2

Does this mean that pins 7 and 8 are a TTL serial RX/TX pair that 
function the same as J2...but without going thru the Sipex TTL-to-RS232 
converter?  That would be a score for those of us who want to use these 
things with Arduinos.

If I get up the courage after my BSOD fun...I may have to try it.

Time to find that disposable laptop I've got somewhere around here... 
The LMU300 can BSOD that thing all it wants!  ;)

thanks much,

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