docs: document the 2.6.3 release image's preconfigured hardware settings

docs/source/sd_card.rst

@@ -140,13 +140,10 @@ than usual, because it expands the filesystem to fill the card.  Give it a coupl
 of minutes.
 
 .. important::
-   After swapping the card you usually need to set the **Camera Type** again.  A
-   freshly imaged card defaults to one sensor, and if it doesn't match your
-   PiFinder the camera view is blank.  From the main menu, select Settings,
-   scroll down to Advanced, then select Camera Type.  A rev4 PiFinder takes
-   ``v3 - imx462``.  There is no separate rev4 entry, and that one is correct.
-   The v3 sensors are ``v3 - imx462`` and ``v3 - imx296``, and older v2 cameras
-   are ``v2 - imx477``.  Then **turn the PiFinder fully off and on again**,
-   because a software restart alone won't apply the change.  See
-   :ref:`troubleshooting:the camera view is blank or black` for more.  Re-check
-   your WiFi settings too.  They don't carry over to a freshly imaged card.
+   A freshly imaged card comes set up for a rev4 PiFinder in the right-hand
+   position: **Camera Type** ``v3 - imx462``, **GPS Baud Rate**
+   ``115200 (UBlox-10)``, and **PiFinder Type** ``Rev4 Right``.  If that
+   doesn't describe your PiFinder, correct these settings after the first
+   boot.  :ref:`software:match the settings to your pifinder` covers what to
+   change on each PiFinder.  Re-check your WiFi settings too.  They don't
+   carry over to a freshly imaged card.

docs/source/software.rst

@@ -50,6 +50,41 @@ The image files on our release pages bundle the correct Raspberry Pi OS version,
 
 Once the imager finishes writing, insert the SD card into your PiFinder and turn it on.  The first boot takes longer than usual, because the PiFinder expands the filesystem to fill the card.  Be patient.
 
+Match the Settings to Your PiFinder
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Release images from v2.6.3 onward come set up for a rev4 PiFinder in the right-hand
+position:
+
+* **Camera Type** is ``v3 - imx462``
+* **GPS Baud Rate** is ``115200 (UBlox-10)``
+* **PiFinder Type** is ``Rev4 Right``
+
+.. note::
+   ``v3 - imx462`` is correct for a rev4 PiFinder.  The rev4 camera uses the same sensor
+   as a v3, so there is no separate rev4 entry.
+
+If that describes your PiFinder, there is nothing to change.  For any other PiFinder,
+correct these settings after the first boot.  From the main menu, select Settings, scroll
+down to Advanced, then:
+
+* Select PiFinder Type and select the entry that matches your PiFinder and its position.
+  A wrong type reverses the Push-To directions.  See :ref:`quick_start:configuration setup`
+  for what each entry means.
+* On a v3 or v2.5 PiFinder, select GPS Settings, then GPS Baud Rate, and set it to
+  ``9600 (standard)``.  These PiFinders have an older GPS receiver.  At the wrong baud
+  rate the GPS never locks.
+* On a v3 PiFinder, check the Camera Type.  A v3 ships with either the ``v3 - imx462``
+  or the ``v3 - imx296`` sensor.  If yours has the imx296, select ``v3 - imx296``, then
+  turn the PiFinder fully off and on again.  A software restart alone won't apply a
+  camera change.  If you're not sure which sensor you have, leave the setting alone.  A
+  blank camera view means you have the other sensor, so select it and turn the PiFinder
+  fully off and on again.  See :ref:`troubleshooting:the camera view is blank or black`.
+  A v2.5 PiFinder with its original camera takes ``v2 - imx477``.
+
+A rev4 PiFinder rotated to the left or straight-back position needs only the PiFinder
+Type change.  The camera and GPS settings already match.
+
 The software is now installed.  Continue to the :doc:`Quick Start Guide<quick_start>` for a night of observing.
 
 Build From Scratch

docs/source/troubleshooting.rst

@@ -170,6 +170,19 @@ was cut short.
 - **Don't compare it with your phone.**  Phones use assisted GPS over the mobile network, so
   they lock in seconds.  That comparison says nothing about your PiFinder or your sky.
 
+One setting can stop a lock outright.  On a v3 or v2.5 PiFinder running a freshly imaged
+card, check the **GPS Baud Rate**.  The release image sets ``115200 (UBlox-10)``, which
+suits the rev4 receiver.  The older receiver in these PiFinders needs ``9600 (standard)``.
+At the wrong baud rate the GPS never locks, no matter how long you wait.
+
+The :ref:`user_guide:status screen` shows this problem directly.  Its GPS MSG row names
+the last message from the GPS receiver, with how long ago it arrived.  From the main menu,
+select Tools, then Status, and scroll down to GPS MSG.  Watch it for a few seconds.  On a
+healthy link the names change constantly and the age stays under a second.  Names that
+start with ``?`` mean data is arriving that the PiFinder can't decode.  That is the sign
+of a wrong baud rate.  To fix it, from the main menu select Settings, scroll down to
+Advanced, select GPS Settings, then select GPS Baud Rate.
+
 If you would rather not wait, enter your location and time by hand and start observing.  See
 :ref:`user_guide:place & time`.  For what the lock types mean, see
 :ref:`user_guide:getting a gps lock`.

docs/source/user_guide.rst

@@ -1044,6 +1044,11 @@ Some of the key information shown:
   the number of stars matched.
 - WiFi information a bit further down, including the current WiFi mode, network name, and
   IP address.
+- The GPS rows near the bottom.  The list is longer than the screen, so scroll down to
+  see them.  GPS MSG names the last message from the GPS receiver, with how long ago it
+  arrived.  On a healthy link the names change constantly and the age stays under a
+  second.  A frozen name with a climbing age, or names starting with ``?``, point to a
+  GPS problem.  See :ref:`troubleshooting:the gps never locks`.
 
 Place & Time
 ----------------------------------