Re: u-blox : layers are confusing me

[Hans Mayer]

Yo Gary, et al,


> ... The "layer" in VAL_SET is not an integer like you are thinking, 
it is a bit map.....

Ok, this I didn't realise. Now is everything clear.  Is this described 
anywhere? I didn't see it. But probably it is.

I understand, "0" as bitmap does nothing.

But why is parameter "1" in ubxtool changing layer 0 which is RAM ?

It must be:

        0 - nothing
        1 - set layer 0 (ram)
        2 - set layer 1 (bbr)
        3 - set layers 0 and 1
        4 - set layer 2 (flash)
        5 = set layers 0 and 2
        6 - set layers 1 and 2
        7 - set layers 0, 1, 2


>... Spend some quality time reading Section 5.3 of this

I did, not only once, but didn't find the answer.


> ... Does my explanation above help? ...

Absolut. Gary, your help is always extremely helpful.


Kind regards

Hans


--



On 20.05.23 20:40, Gary E. Miller wrote:
> Yo Hans!
>
> On Sat, 20 May 2023 15:43:51 +0200
> Hans Mayer <gpsd@ma.yer.at> wrote:
>
> > U-blox ZED-F9P with version 27.12
> Nice.  What port are you using?  The USB?  Serial?  I2C?


Serial. It is a hat from uputronics connected to the GPIO serial port on 
a Raspberry PI 4


> > gpsd: 3.25.1~dev (revision release-3.25-48-gfa2081388)
> Good.  The next thing I need is the complete, untouched, output of:
>          ubxtool -p CONFIG
>          ubxtool -p STATUS
>
> > I am trying to understand the layers, especially with the baudrate
> > configuration.
> Good luck.  The new u-blox layers confuse everyone.
>
> The short answer is that every value actually has 7 layers, and the
> value set in the highest priority layer wins.  Spend some quality time
> reading Section 5.3 of this:
>
>      'ZED-F9P_InterfaceDescription_(UBX-18010854).pdf'
>
> > This is the situation after a RESET
> Which kind of RESET?  There are many kinds, each slightly different.


ubxtool -p RESET localhost:gpsd:/dev/serial0


> > UBX-CFG-VALGET:
> >    version 1 layer 0 position 0
> >     layers (ram)
> >       item CFG-UART1-BAUDRATE/0x40520001 val 38400
> One of the 4 possible layers, you only retrieved the value from layer 0
> (RAM).  A speed of 38.400
>
> > UBX-CFG-VALGET:
> >    version 1 layer 7 position 0
> >     layers (default)
> >       item CFG-UART1-BAUDRATE/0x40520001 val 38400
> One of the 4 possible layers, you only retrieved the value from layer 7
> (default).  A speed of 38.400
>
> > /ubxtool -z CFG-UART1-BAUDRATE,115200,0 localhost:gpsd:/dev/serial0 /
> >
> > and I am wondering why gpsd can still access the device with 38400 bd
> If you look at the doc for UBX-VAL-SET, you'll see you can never set
> layer 0.  Layer 0 is computed from the other layers.
>
> The "layer" in VAL_SET is not an integer like you are thinking, it is
> a bit map.  Bit 1 is to set layer 1, bit 2 is to set layer 2, and bit
> trhee is to set layer 4.
>
> So the layer value can be 0 to 7, each with this result:
>          0 - nothering
>          1 - set layer 1
>          2 - set layer 2
>          3 - set layers 1 and 2
>          4 - set layer 4
>          5 = set layers 1 and 4
>          6 - set layers 2 and 4
>          7 - set layers 1, 2 and 3
>
> Are you sure you have Battery Backed Ram (BBR) on your board?
>
> > /ubxtool -z CFG-UART1-BAUDRATE,115200,1 localhost:gpsd:/dev/serial0/
> >
> > Now communications is broken to the ZED-F9P. I have to reconfigure
> > the gpsd with 115200 bd
> As expected and documented.
>
> > The ZED-F9P interface
> > description PDF is in general very useful but didn't give me a
> > solution for my question.
> I'm unclear exxactly what your question is?
>
> Does my explanation above help?
>
> > It seems there is sometimes an offset of 1 but not always
> u-blox layers have vexxed many people.  The answers really are in the doc.
>
> RGDS
> GARY
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>         gem@rellim.com  Tel:+1 541 382 8588
>
>             Veritas liberabit vos. -- Quid est veritas?
>      "If you can't measure it, you can't improve it." - Lord Kelvin