Your radio has a dozen switches and you’re using maybe four of them. The rest sit idle while you fumble through the OSD menu to change VTX power or toggle between PID profiles. EdgeTX’s logic switch system can automate nearly every repetitive radio action, and if you’re not using it, you’re leaving capability on the table that makes flying smoother and crashing less painful.
Logic Switch Fundamentals
EdgeTX logic switches evaluate conditions and output a binary on/off signal. They can reference physical switches, channel values, telemetry data, timers, and other logic switches. The key types for FPV:
AND / OR Logic
Stack two or more physical switches into a single logical output. The classic use case: a pre-arm chain that requires two momentary switches held simultaneously. This prevents accidental arming when you toss the radio in a bag.
Setup:
– L01: AND, SW1=SH↓, SW2=SF↓
– Assign L01 as your Arm channel source in the Mixes tab
Sticky (SR Flip-Flop)
A Sticky switch toggles state like a physical latching switch but driven by momentary inputs. Edge-triggered: one momentary switch sets it ON, another sets it OFF.
Use case — auto-turtle-mode activation triggered by crash angle:
– L02: Sticky, V1=SH↓ (set ON), V2=L03 (set OFF)
– L03: Timer, 30 seconds (auto-cancel turtle mode after 30s)
Edge
Edge logic fires on a transition — rising edge (off→on), falling edge (on→off), or both. This is how you trigger one-shot actions: play a track, take a screenshot, increment a counter.
Delta (Δ)
Delta compares two values and triggers when their difference exceeds a threshold. Useful for telemetry-based alerts: trigger a haptic pulse when RSSI drops below 50, or when pack voltage crosses a threshold at a specific rate of change (sag detection).
Setup:
– L04: Delta, V1=RxBt (pack voltage), V2=12.0V (3.0V/cell on 4S), Direction=↓
– Special Function: SF1, L04, Play Track “battery low”
Timer
Timer logic switches fire after a delay. Chain with Sticky for auto-cancel functions.
Parameter Reference
| Logic Type | Best Use Case | Common Pitfall | EdgeTX Version |
|---|---|---|---|
| AND | Pre-arm chain (2 switches) | Doesn’t handle momentary well alone — combine with Sticky | All |
| OR | Multi-condition alerts | Can fire unexpectedly if conditions overlap | All |
| Sticky | Latching from momentary inputs | Needs a clear OFF condition; without one it latches permanently | All |
| Edge | One-shot trigger on transition | Both-edge (BOTH) fires twice per button press; use ↑ or ↓ only | All |
| Delta | Telemetry threshold alerts | Small threshold values trigger on noise — add hysteresis | 2.8+ |
| Timer | Auto-cancel, countdown | Timer resets if source condition changes mid-count | All |
| Comparator (a>x) | Value thresholds | Integer comparison only; 3.5V rounds to 3 | All |
Step-by-Step: Building a Pre-Arm Chain
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Choose your switches. I use SH (top-right momentary) and SF (top-left 2-pos) as the physical pre-arm pair. SH requires continued pressure, SF stays latched.
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Create L01 — AND gate. Navigate to LOGICAL SWITCHES → L01. Set Func=AND, V1=SH↓, V2=SF↓. The ↓ suffix means “active when switch is in the down position.” Without it, the logic evaluates based on switch position numbering, which varies by radio model.
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Create L02 — Sticky latch. Set Func=Sticky, V1=L01, V2=!L01. This latches ON when both switches are held and turns OFF when either is released. The “!” means “NOT L01” — the inverse.
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Assign to channel. In MIXES, edit CH5 (or your Arm channel). Set Source=L02. Now the channel outputs +100 when L02 is ON and -100 when OFF.
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Add audio feedback. SPECIAL FUNCTIONS → SF1. Switch=L02, Action=Play Track, Track=”armed” (or a custom .wav). SF2: Switch=!L02, Track=”disarmed”. You now have audible confirmation every time the arm state changes.
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Test in Betaflight Receiver tab. Verify CH5 swings from 988 to 2012 on pre-arm, and returns to 988 when either switch is released.
Advanced: Building a Flight Mode Sequencer
Instead of a 3-pos switch cycling Angle → Horizon → Acro, build a logic sequencer that cycles through modes with a single momentary button:
- L10: Sticky, V1=SH↓, V2=SH↓ (toggles OFF on second press)
- L11: Sticky, V1=L10 AND L12 is OFF
- L12: Sticky, V1=L10 AND L11 is ON
- Assign L11 and L12 to a channel with weighted mixing: Mode ch = (L11 × 50) + (L12 × 100) produces three distinct values (0, 50, 100) mapping to three flight modes.
What Most Pilots Get Wrong
Mistake 1: Using physical switch position directly for pre-arm
The consequence: A single 2-pos switch arms the quad. It gets bumped in the bag, you plug in, and the quad arms inside a confined space. The fix: Pre-arm chains must require at least one momentary switch held in a deliberate position. Two-momentary or momentary-plus-latched patterns prevent accidental arming entirely.
Mistake 2: Forgetting the OFF path in Sticky switches
The consequence: A Sticky switch latches ON and never turns off because no OFF condition was defined. You power-cycle the radio and it comes back in the same state. The fix: Every Sticky switch needs an explicit OFF condition. The simplest pattern: the same switch that turns it ON also turns it OFF (momentary toggle), or a separate switch/condition that forces it OFF.
Mistake 3: Using Delta on raw telemetry without averaging
The consequence: RSSI telemetry fluctuates ±3dB in normal flight. A Delta trigger set to fire at RSSI < 50 fires 10 times per minute on rapid RSSI dips that last 50ms. The fix: Apply a filter in the telemetry settings (Sensor → Filter → 3-5 sample average) or use a Timer logic switch to require the condition to persist for 2+ seconds before triggering.
Mistake 4: Stacking too many logic layers without testing each in isolation
The consequence: L05 references L04, which references L02, which references a telemetry value that isn’t populated on the bench. The entire chain silently fails and you don’t know why. The fix: In the LOGICAL SWITCHES screen, the “State” column shows live ON/OFF status for each logic switch. Test each layer individually — trigger V1 and V2 manually and verify the output changes before building the next layer.
⚠️ Regulatory Notice: Custom switch programming on your radio transmitter is part of your UAS control system configuration. In the US, FAA regulations require that the pilot maintain positive control of the aircraft at all times — automated switch sequences that could interfere with this requirement should be tested thoroughly and include an immediate manual override path. Some jurisdictions require that critical flight functions (arm/disarm, flight mode) be directly accessible without complex switch sequences. Always verify your transmitter configuration complies with the latest 2026 operating rules for your region.
Internal Resources
After setting up your switches, you’ll want to verify the channel outputs in Betaflight. Our Betaflight OSD configuration guide covers adding channel monitors to your display so you can see mode changes in the goggles. For ExpressLRS users, our ELRS 3.x flashing guide covers keeping your receiver firmware current so it correctly interprets the channel ranges your EdgeTX logic switches produce. The failsafe configuration guide ensures your custom switch assignments don’t interfere with the failsafe detection thresholds.
Recommended Video
Joshua Bardwell’s deep dive into EdgeTX logic switches demonstrates every type with real radio screen recordings:
One Radio to Rule Them
Logic switches are great on paper, but they’re only as good as the gimbals and switches feeding them inputs. The Radiomaster TX16S Mark II with the AG01 hall-effect gimbals gives you 16 physical inputs with customizable tension and travel — and the EdgeTX touchscreen makes configuring logic chains 10x faster than wheel navigation. If your current radio has drifting potentiometers or sticky switches that fire false edges, your logic chains are only as reliable as the hardware they run on.