Making a parameter "Used" (therefore visible in QGroundControl)

K4rolis 2019-02-07 11:26:55 UTC #1

Hi,

What does it take for a parameter to become used?

I know I've defined it correctly (in parameters.c under my sensor driver subdir and it is visible under build/build_name/parameters.xml with correct annotations), I've also referenced the parameter in ROMFS/px4fmu_common/init.d/rc.sensors (as the parameter itself is a simple on/off switch for a sensor driver), but it is not visible in QGroundControl and param show in nsh does not mark it as used.

If I reference it in ROMFS/px4fmu_common/init.d/rcS (the reason why I tried that is that the only distance sensor-related parameter visible in QGroundControl is for LL40LS and it is referenced in rcS), my parameter DOES become used, however the annotations in QGC are missing (i.e. it seems that I can change the value, but I don't get nice drop-down).

Thank you in advance!

Karolis

JulianOes 2019-02-07 12:48:32 UTC #2

So I learnt yesterday in the dev call that in order for a param to show up the call param_find needs to happen before the last rcS item which is mavlink boot_complete.

So if you somehow make sure that your parameter is "used" with param_find before that, then it should work.

github.com

PX4/Firmware/blob/7f3b170024222cb9c8a4964afaa3e74d3e6f52c2/ROMFS/px4fmu_common/init.d/rcS#L520


unset PWM_MIN
unset PWM_OUT
unset PWM_RATE
unset SDCARD_MIXERS_PATH
unset USE_IO
unset VEHICLE_TYPE


#
# Boot is complete, inform MAVLink app(s) that the system is now fully up and running.
#
mavlink boot_complete

K4rolis 2019-02-07 13:29:00 UTC #3

Thank you, that explains why adding a check on a parameter in rcS solves it - LL40LS has a check in that file, which marks it as used. Core thing here is that my flight controller is running with SYS_HITL as Enabled, meaning rc.sensors never gets executed.

Now the question is - why are the annotations not picked up? I only get to enter the raw value.

Also, is there documentation on sensors app? In particular, the behaviour of -h flag.

JulianOes 2019-02-07 17:46:49 UTC #4

This describes the sensors args:
https://dev.px4.io/en/middleware/modules_system.html#sensors

The annotations land in QGC on new releases when the latest xml file is copied into the source:

github.com

mavlink/qgroundcontrol/blob/master/src/FirmwarePlugin/PX4/PX4ParameterFactMetaData.xml

<?xml version='1.0' encoding='UTF-8'?>
<parameters>
  <version>3</version>
  <parameter_version_major>1</parameter_version_major>
  <parameter_version_minor>15</parameter_version_minor>
  <group name="UAVCAN Motor Parameters" no_code_generation="true">
    <parameter default="75" name="ctl_bw" type="INT32">
      <short_desc>Speed controller bandwidth</short_desc>
      <long_desc>Speed controller bandwidth, in Hz. Higher values result in faster speed and current rise times, but may result in overshoot and higher current consumption. For fixed-wing aircraft, this value should be less than 50 Hz; for multirotors, values up to 100 Hz may provide improvements in responsiveness.</long_desc>
      <unit>Hertz</unit>
      <min>10</min>
      <max>250</max>
    </parameter>
    <parameter default="1" name="ctl_dir" type="INT32">
      <short_desc>Reverse direction</short_desc>
      <long_desc>Motor spin direction as detected during initial enumeration. Use 0 or 1 to reverse direction.</long_desc>
      <min>0</min>
      <max>1</max>
    </parameter>
    <parameter default="1" name="ctl_gain" type="FLOAT">

This file has been truncated. show original

I don't think it's updated otherwise but I might be mistaken.

K4rolis 2019-02-11 15:24:39 UTC #5

Thank you, this makes sense!