> For the complete documentation index, see [llms.txt](https://docs.theseus.us/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.theseus.us/cyclops/developers/qgc-home-position-sender.md).
# QGC home position sender
This setup adds a QGroundControl Fly View action that tells an ArduPilot Lua script to send the flight controller's home position to the Cyclops computer.
## Components
* `../home_position_sender.lua` runs on the flight controller. It accepts either `COMMAND_LONG 31000` or a marker request (`COMMAND_LONG 512` with `param1=242`, `param2=31000`), reads the FC home position, then sends `MAV_CMD_DO_SET_HOME` to the Pi at sysid `218`, compid `190`.
* `FlyViewCustomActions.json` runs on the QGC computer. It adds the `Send Home to Pi` action in Fly View and sends command `31000` to the active vehicle.
## Flight controller setup
{% stepper %}
{% step %}
## Enable Lua scripting
Enable ArduPilot Lua scripting (`SCR_ENABLE=1`) and reboot the flight controller.
{% endstep %}
{% step %}
## Home position sender script
{% file src="/files/PUPmXn3Vu2BUpjtkp36i" %}
Copy `home_position_sender.lua` to the flight controller SD card:
```
/APM/scripts/home_position_sender.lua
```
{% endstep %}
{% step %}
## MAVLink Lua modules
Copy the MAVLink Lua modules to:
```
/APM/scripts/modules/MAVLink/
```
At minimum, this script needs:
```
mavlink_msgs.lua
mavlink_utils.lua
mavlink_msg_COMMAND_LONG.lua
mavlink_msg_COMMAND_ACK.lua
mavlink_msg_HEARTBEAT.lua
```
{% endstep %}
{% step %}
## Reboot
Reboot the flight controller or restart scripting.
{% endstep %}
{% endstepper %}
## Home and estimator-origin
The script has deterministic home selection logic:
1. Use `vehicle:home()` first.
2. Use `ahrs:get_home()` only if `vehicle:home()` did not return a home object.
What this means operationally:
* The script sends only the selected home position (`lat/lon`) to the Pi.
* The device will use the terrain data from onboard maps to determine altitude.
* Estimator origin coordinates are never sent to the Pi by this script.
* Estimator origin must be initialized at least once before the home position is considered valid.
* Home position and estimator origin do not need exact coordinate equality, but they must be in the same operating area.
* If estimator origin is not initialized, or home resolves to an invalid value (`nil` or `0,0`), the script does not send `MAV_CMD_DO_SET_HOME` and QGC can show a timeout.
Expected startup message:
```
Home Sender ready (REQUEST_MESSAGE marker 31000, ... MAV channels)
```
## QGroundControl setup
{% file src="/files/DpHkpve7GGRTMLYIVYob" %}
Copy `FlyViewCustomActions.json` to QGC's MAVLink actions directory.
```
~/Documents/QGroundControl/MavlinkActions/FlyViewCustomActions.json
```
Restart QGC after copying the file.
## Testing the feature
{% stepper %}
{% step %}
### Set estimator origin
Click on the map and select "*Set Estimator Origin*"
{% endstep %}
{% step %}
### Set home
Click on the map and select *"Set home here"*
{% endstep %}
{% step %}
### Send home to Pi
In Fly View, open the Actions menu and click *"Send Home to Pi"*
\
You should see the VPS startup status text messages in the MAV messages when the VPS restarts.
{% endstep %}
{% endstepper %}
## References
* ArduPilot Lua scripting:
* ArduPilot MAVLink command Lua example:
* QGC custom MAVLink actions:
