Configuring a iFlight Commando 8 radio transmitter

[Enric Cervera Mateu]

Hardware: (board / drone / SKU, serial # if you have it)
VOXL 2 Starling Indoor and Outdoor
SLAM & Autonomy Development Dr-
one
with 2 Batteries, Controller and Case
SKU: MRB-D0005-4-V2-C6-M22-K3

Board replaced with:
VOXL 2
Board Only
SKU: MDK-M0154-1-00
HS Code: 8542310000

What I am trying to do:
We have lost the original controller and we want to replace it with an
iFlight Commando 8 Radio Transmitter ELRS V2:
https://iflight-rc.eu/en-es/products/commando-8-radio-transmitter-elrs-v2?variant=44711163298057

How can we install the modalai firmware in the controller?

Thanks.

[Alex Kushleyev]

Hello @enric-cervera-mateu ,

Good news: you don't need to install any special ModalAI firmware on the iFlight Commando 8. ModalAI does not provide transmitter firmware — the Commando 8 ships pre-loaded with EdgeTX and a built-in ELRS module, which is exactly what you need to control a VOXL 2 Starling.

Here is what you actually need to do:

1. Make sure you have the right frequency variant

The Starling V2 ships with a 915 MHz BetaFPV ELRS receiver. You must use a Commando 8 with a matching band:

• If your drone has the 915 MHz receiver → get the iFlight Commando 8 ELRS 868/915 MHz V2
• If your drone has a 2.4 GHz receiver → get the iFlight Commando 8 ELRS 2.4 GHz V2

Mixing bands (e.g., 2.4 GHz TX with 915 MHz RX) will prevent binding entirely.

2. Match ELRS firmware versions

The ELRS firmware version on the transmitter module and the receiver must share the same major version (e.g., both on 3.x). Mixing 3.x and 2.x is not supported.

• Check the TX firmware version in EdgeTX: go to SYS → Hardware → TX Module or the ELRS Lua script.
• Check the receiver firmware version via the voxl-elrs tool on the drone (see Step 4).
• If versions don't match, update both using the ExpressLRS Configurator for the TX module, and voxl-elrs for the receiver.

3. Bind the transmitter to the receiver

Two methods work with ELRS:

Method A — Binding phrase (recommended):
Both the TX module and receiver must be flashed with the same binding phrase. If the original controller used a binding phrase, you'll need to reflash the receiver on the drone with a new phrase that matches what you set on the Commando 8.

Method B — Button bind:

1. Power on the drone. Within 30 seconds, press and hold the bind button on the ELRS receiver.
2. On the Commando 8, start binding from the ELRS Lua script (Tools menu in EdgeTX).
3. The receiver LED will change when binding succeeds.
4. Power-cycle the drone after binding. (Skipping this step causes "Detected 0 radio channels" errors.)

4. Configure the VOXL 2 software

SSH into the VOXL 2 and edit the PX4 configuration file:

vi /etc/modalai/voxl-px4.conf

Set the RC protocol to CRSF:

RC=CRSF_RAW

Then restart the PX4 service:

systemctl restart voxl-px4

5. Verify RC input

After binding and restarting, verify channels are publishing:

px4-listener input_rc

If no channels appear, check:

• Power-cycle was done after binding
• journalctl -b -u voxl-px4 for driver errors
• Physical wiring on connector J19 (receiver TX → RC_UART_RX, receiver RX → RC_UART_TX, 5V, GND)

Wiring reference (J19 on VOXL 2)

Receiver pin	VOXL 2 J19 pin
5V	VDC_5V_LOCAL
GND	GND
TX	RC_UART_RX
RX	RC_UART_TX (needed for voxl-elrs firmware updates)

---

For the full wiring diagram and RC configuration reference, see the official docs:

• RC Configs: https://docs.modalai.com/voxl2-rc-configs/
• voxl-elrs tool: https://docs.modalai.com/voxl-elrs/

If you continue to have binding issues (particularly if the receiver is still bound to the original lost controller), you may need to reflash the receiver to clear the old binding phrase. The voxl-elrs tool can help with this for BetaFPV receivers.

Sources

• https://docs.modalai.com/voxl2-rc-configs/ — VOXL 2 RC controller configuration, wiring, supported protocols
• https://forum.modalai.com/topic/3066/elrs — ModalAI forum thread on ELRS setup with VOXL 2 Starling
• https://forum.modalai.com/post/17958 — Forum post on switching Starling 2 from Ghost Atto to ELRS
• https://shop.iflight.com/Commando8-Radio-Transmitter-ELRS-V2-Pro2092 — iFlight Commando 8 ELRS V2 product page
• https://github.com/ExpressLRS/ExpressLRS — ExpressLRS project (for Configurator tool)