ELRS Binding
ExpressLRS replaced button-dance binding with an idea from cryptography: a bind phrase. Flash the same phrase into the transmitter and every receiver you own, and they simply know each other — new receivers bind by construction, nothing to redo at the field, nobody else's radio can talk to your quad.
🟢 Start — the two rules that prevent 90 % of problems:
- One bind phrase, everywhere, forever. Pick something unique to you, set it in the ELRS Configurator, use it for every TX module and RX you ever flash.
- TX and RX firmware must match on major.minor (e.g. 3.4.x with 3.4.x). A mismatch doesn't degrade politely — it usually just doesn't link. When binding mysteriously fails, check versions first.
The flow, per device
| Device | How it's flashed | Notes |
|---|---|---|
| TX module (in the radio) | ELRS Configurator over USB, or its own WiFi | Set bind phrase + regulatory domain |
| Receiver (on the quad) | Easiest: WiFi — power the RX, wait ~60 s, it opens a hotspot; upload firmware from the browser | Same phrase, same major.minor as the TX |
After both carry the phrase: power the quad, and the radio's ELRS screen shows a connection within seconds. In Betaflight, the Receiver tab bars move — if they don't, the RX is bound but the FC isn't listening (Betaflight basics: Ports tab, Serial RX).
🟡 Hands-on — the settings that matter after binding:
- Packet rate: 250 Hz is the freestyle default; 50 Hz roughly doubles range at the cost of latency — the sensitivity math lives on the receiver page. Match your Betaflight RC link preset to whatever you pick (Betaflight basics).
- TX power: more is legal-limited, battery-hungry and rarely the fix — Module 1 shows antennas and packet rate buy more, dB for dB. Dynamic power is the sane default: high when needed, cool otherwise.
- Model match: ties this RX to one EdgeTX model, so the right settings load and the wrong quad can't arm (Radio Transmitter).
- Telemetry rides the same link back: link quality for your OSD, plus voltage as a backup to the FC's own sensing.
When it won't bind
| Symptom | Usual cause | Fix |
|---|---|---|
| No link at all | major.minor mismatch | Reflash the RX to the TX's version |
| No link, versions match | Bind phrase typo'd on one end | Reflash with the exact phrase — it's case-sensitive |
| Links, then drops on arming | RF interference from VTX right next to RX antenna | Antenna placement — Receiver |
| RX WiFi never appears | It's bound and linked already (WiFi only starts without a link) | Turn the radio off, power the quad, wait 60 s |
| Radio shows link, Betaflight bars dead | UART/Ports misconfigured | Betaflight basics, Ports tab |
Any day you reflash or rebind anything, re-run the bench failsafe test before the next flight — radio off, motors stop (Receiver). Link plumbing changes are exactly when failsafe assumptions silently reset.
Where this connects
- Radio Receiver — packet rates, sensitivity, RSSI vs LQ
- Radio Transmitter — the TX-side settings and model match
- Flashing firmware — the general flashing discipline this inherits
- Module 1 — Radio & links — why the range levers rank the way they do