Solid on
Bound and connected
- Cause
- All good
- Fix
- Nothing. Fly.
Free guide
Binding ELRS, and what the LED means
Binding is where new builders stall. The radio says one thing, the receiver blinks something else, and nothing in either manual connects the two. This is the whole procedure, plus the decoder for every LED pattern you are likely to see.
What this covers
- Radios
- RadioMaster Boxer and Pocket
- Firmware
- ExpressLRS 4.0.x
- Receivers
- RP1, RP2, RP4TD, EP1, EP2, BETAFPV Nano
- Configurator
- Betaflight Configurator 10.11.x desktop / 2025.12.x web
Print the one-page sheet (PDF)
Version numbers matter here more than almost anywhere else in FPV. A radio on 4.0.x will not bind to a receiver still on 3.x, and the symptom is a blink pattern rather than an error message.
The receiver LED decoder
Find your blink pattern. Almost every bind problem is one of these.
Slow blink (1 Hz)
Bind seeking
- Cause
- First-power bind mode, or a double power-cycle entered bind mode
- Fix
- Is the radio in bind mode? Does the bind phrase match?
Fast blink (10 Hz)
Connected, low link quality
- Cause
- Noisy RF environment, or a damaged antenna
- Fix
- Move the radio closer. Check the antennas are intact, then reboot.
Double blink
No bind packets received
- Cause
- Bind phrase mismatch between radio and receiver
- Fix
- Re-enter the bind phrase on the radio. Type it out. Compare character by character.
Triple blink
Major version mismatch
- Cause
- Radio on ELRS 4.0.x, receiver still on 3.x
- Fix
- Flash the receiver to 4.0.x — chapter 8 has the procedure.
Off, no LED
No power
- Cause
- Wiring fault, blown receiver, or reversed polarity
- Fix
- Check for 5 V on the receiver pads. Continuity meter first, then look at the joint.
Brief flicker
Power cycling
- Cause
- Brown-out or poor wiring under load
- Fix
- Check pack voltage and the FC's BEC output. Re-solder if the joint looks dull.
Anything else
Hardware-specific status
- Cause
- Vendor-specific pattern
- Fix
- Check the manufacturer's datasheet. Most elaborate patterns are vendor status codes.
Set the radio up first
Create the model
System → MODEL → Create model. Pick the template "Multirotor — ELRS", then confirm on the model select screen.
Name it
Page right to MODEL SETUP. Set a name you will recognise three months later — "5inch-2026" beats "model 03". Model number and image are optional.
Internal module → CRSF
MODEL SETUP → Internal RF. Type: CRSF. This is the moment the radio's internal ELRS module wakes up; channel ranges populate automatically.
Bind phrase
SYS → Tools → ExpressLRS → Bind Phrase. Enter something memorable — 6–32 characters, ASCII only. Write it down somewhere that is not the radio.
Packet rate
Tools → ExpressLRS → Packet Rate. 250 Hz for indoor whoops and 5-inch freestyle (the default), 500 Hz for racing, 100 Hz for long range. Higher rate means lower latency and less range.
Save and exit
Long-press EXIT to return to the model screen, then power-cycle the radio so the bind phrase change applies.
The bind phrase. The bind phrase lives on the radio AND on the receiver, and both must match: same string, exactly, case-sensitive, no trailing spaces.
Bind the receiver
On the radio
- Power on the radio.
- System → Tools → ExpressLRS → Bind.
- The internal module starts transmitting the bind packet. The screen shows "BINDING…" and the bind LED on the antenna housing pulses.
- Wait. Do not power-cycle.
On the receiver
- Apply power for the first time after a fresh flash and it enters bind mode automatically. On a receiver that is not freshly flashed, force it: power up, power down within two seconds, power up again.
- The receiver LED enters the bind-seeking pattern — see the decoder below.
- When the bind packet reaches the receiver, the LED switches to solid within one to three seconds.
- The receiver is now bound to this bind phrase.
Verify in Betaflight
- Power the flight controller over USB, open Configurator and connect.
- Open the Receiver tab and confirm Serial Provider is CRSF.
- Power the FC from a pack — props off, on the bench — so the receiver wakes.
- Move the sticks. The channel bars should move with them.
- If they do not move, work the LED decoder below.
Model match. Model match is optional and off by default. Turned on, the receiver only listens to the radio's currently selected model, which is useful once you fly several quads. EdgeTX → Tools → ExpressLRS → Model Match.
The AUX channel map the book recommends
| Channel | Mode | Switch | Active range |
|---|---|---|---|
| AUX1 (ch 5) | ARM | SA (2-position) | 1700–2100 |
| AUX2 (ch 6) | ANGLE5-inch optional | SB (2-position) | 1700–2100 |
| AUX3 (ch 7) | PREARM | Momentary trim or button | 1700–2100 |
| AUX4 (ch 8) | BEEPER | SC (2-position) | 1700–2100 |
| AUX5 (ch 9) | BLACKBOX | SD (3-position, top) | 1700–2100 |
| AUX6 (ch 10) | GPS RESCUE5-inch only | SD (3-position, middle) | 1300–1700 |
| AUX7 (ch 11) | FLIP / TURTLE | SE (2-position) | 1700–2100 |
| AUX8 (ch 12) | Spare / reserved | — | — |
The book is opinionated, not religious. If your hand prefers ARM on SB and BEEPER on SA, run the swap and set the aux lines to match. The pattern that matters is deliberate switches with ranges that never overlap.