# Playing with VFC

Source: https://forum.modalai.com/topic/4498/playing-with-vfc
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2025-06-10 22:24:58 UTC by Aaron Porter
Replies: 3 · Views: 766

## Aaron Porter · 2025-06-10 22:24:58 UTC

Hello,

  I am playing around with VFC on one of the Starlings 1. I am able to takeoff in altitude mode and change over to Offboard mode. I thought that changing to offboard mode from altitude would cause the drone to go into VFC_Altitude mode however, I get a message in QGC that the mode is VFC_Manual and feels similar to  manual mode as well. Not sure if I am missing something? Am I wrong in thinking that it should be in VFC_Altitude?

I am using a joystick controller instead of an RC controller. 

Thank you for your time,
Aaron Porter

## Reply by tom (ModalAI staff) · 2025-06-12 18:24:50 UTC

@Aaron-Porter The VFC flight mode that will be entered when switching into offboard is dependant on what is specified in `/etc/modalai/voxl-vision-hub.conf`

Example here:

```
"vfc_submode_ch":	6,
	"vfc_alt_mode_rc_min":	0,
	"vfc_alt_mode_rc_max":	0,
	"vfc_flow_mode_rc_min":	1700,
	"vfc_flow_mode_rc_max":	2100,
	"vfc_hybrid_flow_mode_rc_min":	0,
	"vfc_hybrid_flow_mode_rc_max":	0,
	"vfc_position_mode_rc_min":	1300,
	"vfc_position_mode_rc_max":	1700,
	"vfc_traj_mode_rc_min":	0,
	"vfc_traj_mode_rc_max":	0,
```

In this example, VFC flight modes are monitored on channel 6
Depending on what position the switch is in, a different VFC mode will be entered

So for example, if the middle position of flight modes is set to "Offboard", when the switch is flipped into the middle position ~1500, VFC position mode will be entered

## Reply by Aaron Porter · 2025-06-16 20:42:19 UTC

Thank you, I was playing around with it.
Seems like for the controller it is a bit difficult since all main the buttons on the Xbox controller are mapped to the same channels. But at least then are set to different values.

## Reply by Aaron Porter · 2025-06-20 20:10:01 UTC

So something that I was seeing while testing this was having a bit of instability with Open VINS flying and altitude flying (Not Using VFC). I was seeing that voxl-open-vins-server stated that the IMU temperature was too high and kept resetting. After letting the VOXL2 cool down for a day I was able to have the Drone Fly in VFC mode but not sure how it flew compared to Position mode using VIO.