Re: u-blox : layers are confusing me (Hans Mayer)

[Hans Mayer]

Hi Jason,

thanks for your feedback.

> ... I believe that the U-BLOX GPS unit is auto baud configuring ...

This is not true in my case. If I connect with the wrong baud-rate I get only garbage.

And this is not my question. See my initial post below.

The question is, why is the speed not set for a dedicated given layer. See my detailed tests.

// Hans

--

On 20.05.23 19:40, Jason A. McPeak wrote:

I believe that the U-BLOX GPS unit is auto baud configuring by default. I have accessed mine using Minicom under Linux at all kinds of different speeds, and it always sends clear messages, unlike the GPS devices on commercial ships which if you had your baud rate wrong all you got was garbage sentences.

Message: 3
Date: Sat, 20 May 2023 15:43:51 +0200
From: Hans Mayer <gpsd@ma.yer.at>
To: gpsd-users@nongnu.org
Subject: u-blox : layers are confusing me
Message-ID: 44048f28-0efe-1f04-7a85-58608b5cbf6a@ma.yer.at" moz-do-not-send="true"><44048f28-0efe-1f04-7a85-58608b5cbf6a@ma.yer.at>
Content-Type: text/plain; charset="utf-8"; Format="flowed"


Dear All,

my environment:

U-blox ZED-F9P with version 27.12

gpsd: 3.25.1~dev (revision release-3.25-48-gfa2081388)

Debian GNU/Linux 11 (bullseye)


I am trying to understand the layers, especially with the baudrate 
configuration.


This is the situation after a RESET


UBX-CFG-VALGET:
  version 1 layer 0 position 0
   layers (ram)
     item CFG-UART1-BAUDRATE/0x40520001 val 38400

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

UBX-ACK-NAK:
   NAK to Class x06 (CFG) ID x8b (VALGET)

UBX-ACK-NAK:
   NAK to Class x06 (CFG) ID x8b (VALGET)

UBX-CFG-VALGET:
  version 1 layer 7 position 0
   layers (default)
     item CFG-UART1-BAUDRATE/0x40520001 val 38400

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)


Now I am running

/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

When I look for the settings I get the same result as above. I try it 
with layer 1

/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

I have the following situation, layer 0 has 115200 bd


UBX-CFG-VALGET:
  version 1 layer 0 position 0
   layers (ram)
     item CFG-UART1-BAUDRATE/0x40520001 val 115200

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

UBX-ACK-NAK:
   NAK to Class x06 (CFG) ID x8b (VALGET)

UBX-ACK-NAK:
   NAK to Class x06 (CFG) ID x8b (VALGET)

UBX-CFG-VALGET:
  version 1 layer 7 position 0
   layers (default)
     item CFG-UART1-BAUDRATE/0x40520001 val 38400

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)


Now I do the same with 2

/ubxtool -z CFG-UART1-BAUDRATE,115200,2 localhost:gpsd:/dev/serial0/

and layer 1 (bbr) is changed


UBX-CFG-VALGET:
  version 1 layer 0 position 0
   layers (ram)
     item CFG-UART1-BAUDRATE/0x40520001 val 115200

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

UBX-CFG-VALGET:
  version 1 layer 1 position 0
   layers (bbr)
     item CFG-UART1-BAUDRATE/0x40520001 val 115200

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

UBX-ACK-NAK:
   NAK to Class x06 (CFG) ID x8b (VALGET)

UBX-CFG-VALGET:
  version 1 layer 7 position 0
   layers (default)
     item CFG-UART1-BAUDRATE/0x40520001 val 38400

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

What happens with 3 ?

/ubxtool -z CFG-UART1-BAUDRATE,115200,3 localhost:gpsd:/dev/serial0/

nothing, same config as before

and with 4

/ubxtool -z CFG-UART1-BAUDRATE,115200,4 localhost:gpsd:/dev/serial0/

now layer 2 changed


UBX-CFG-VALGET:
  version 1 layer 0 position 0
   layers (ram)
     item CFG-UART1-BAUDRATE/0x40520001 val 115200

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

UBX-CFG-VALGET:
  version 1 layer 1 position 0
   layers (bbr)
     item CFG-UART1-BAUDRATE/0x40520001 val 115200

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

UBX-CFG-VALGET:
  version 1 layer 2 position 0
   layers (flash)
     item CFG-UART1-BAUDRATE/0x40520001 val 115200

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)

UBX-CFG-VALGET:
  version 1 layer 7 position 0
   layers (default)
     item CFG-UART1-BAUDRATE/0x40520001 val 38400

UBX-ACK-ACK:
   ACK to Class x06 (CFG) ID x8b (VALGET)


I am quite sure there is an explanation. The ZED-F9P interface 
description PDF is in general very useful but didn't give me a solution 
for my question.

It seems there is sometimes an offset of 1 but not always


Kind regards

Hans

--

Jason Allen McPeak (mcpeak.jason@gmail.com)
+1 (281) 673-0865 Mobile
FCC Call sign: KG5CYH (Technician Class)
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