# Betaflight SmartAudio and Tramp VTX Control Setup: Complete Guide
Configuring VTX control through Betaflight is one of the first things every FPV pilot should master. Being able to change your video channel, band, and power level from your radio’s OSD menu or LUA script — without ever touching physical buttons — is a massive quality-of-life upgrade. This guide covers everything from wiring to troubleshooting for both SmartAudio and IRC Tramp protocols.
## SmartAudio vs Tramp: What’s the Difference?
| Feature | SmartAudio (SA) | IRC Tramp |
|———|—————-|———–|
| Developer | TBS (Team BlackSheep) | ImmersionRC |
| Data Wire | Single-wire UART TX only | Single-wire UART TX only |
| Power Levels | 25/200/500/800mW (vendor-defined) | 25/100/200/400/600mW+ (vendor-defined) |
| Pit Mode | Supported via SA 2.0+ | Supported |
| Common Brands | TBS Unify, Rush Tank, AKK | Tramp HV, TBS Unify Pro32 (both) |
| Protocol Version | SA 2.0 or 2.1 | Tramp Protocol |
Most modern VTXs support both protocols. The TBS Unify Pro32 and Rush Tank Ultimate are popular choices that work flawlessly with either.
## Wiring Guide
VTX control requires only **one wire connected to a free UART TX pad** on your flight controller — not RX, not both.
“`
FC UART TX pad ───► VTX SmartAudio / T pin
“`
### Wiring Steps
1. **Identify a free UART**: Check your flight controller pinout. Avoid UART1 (often USB), UART used for receiver (usually RX), and UART used for GPS.
2. **Solder the wire**: Connect the chosen FC UART **TX** pad to the VTX’s **SmartAudio (SA)** or **Tramp (T)** pad.
3. **No ground needed**: The VTX already shares ground through the main power connection.
### Common Flight Controller UART Assignments
| UART | Typical Use | Available for VTX? |
|——|————-|———————|
| UART1 | USB / MSP | Usually no |
| UART2 | Receiver (SBUS/CRSF) | Usually no |
| UART3 | GPS / Open | Yes, if no GPS |
| UART4 | Open | Yes |
| UART5 | ESC Telemetry | Usually no |
| UART6 | Open | Yes, preferred |
## Betaflight Configuration
### Ports Tab Setup
1. Open Betaflight Configurator
2. Go to the **Ports** tab
3. Find the UART you wired VTX control to
4. Under **Peripherals**, select the appropriate protocol:
– **TBS SmartAudio** for TBS Unify, Rush Tank, AKK
– **IRC Tramp** for ImmersionRC Tramp, or any VTX in Tramp mode
5. Click **Save and Reboot**
### Video Transmitter Tab
1. Go to the **Video Transmitter** tab
2. Set the correct VTX table. Most manufacturers provide a JSON file you can load directly:
– Click **Load from file** and select the manufacturer’s VTX table
– Or manually enter each band, channel, and power level
3. Set initial values:
– **Band**: Choose your preferred band (Raceband recommended)
– **Channel**: Set your usual channel (R1/R8 for racing)
– **Power**: Set an initial power level (25mW for bench testing)
### VTX Tables: The Most Common Setup Failure
VTX tables are critical. If your VTX table doesn’t match your hardware, power levels and channels will be wrong.
**Where to find VTX tables**: Most manufacturers provide them on their product page or GitHub. Common sources:
– **TBS**: `tbs-unify-vtx-table.json` on the TBS website
– **Rush**: Available in RushFPV GitHub repository
– **Tramp**: Select “IRC Tramp” with the generic Tramp table (built-in)
## Setting Up OSD VTX Control
### Enabling CMS (Configuration Menu System)
1. Go to **Configuration** tab in Betaflight
2. Enable **OSD (CMS)** if not already enabled
3. Go to **OSD** tab
4. Add the following elements to your OSD layout:
– **VTX Channel** — shows current band/channel
– **Craft Name** — helps confirm you’re on the right quad
### Using the OSD Menu
In your goggles, use your radio sticks:
– **Throttle mid + Yaw left + Pitch forward** → Enter OSD menu
– Navigate to **Features → VTX SA** or **VTX TR**
– Adjust Band, Channel, and Power
– **Yaw right** to confirm changes
– Exit menu with the same stick command
## LUA Script Control (EdgeTX / OpenTX)
LUA scripts let you change VTX settings from your radio screen without entering the OSD menu.
### Steps for ExpressLRS / Crossfire
1. Download the appropriate LUA script:
– **ELRS**: Included in ExpressLRS Configurator → `ELRS.lua`
– **Crossfire**: Built into the TBS Agent Lite LUA
2. Copy to your radio’s SD card: `SD/SCRIPTS/TOOLS/`
3. On your radio, long-press SYS → **Tools** → Run the LUA
4. Navigate to VTX settings and adjust as needed
The LUA communicates over the same CRSF/ELRS telemetry link — no additional wiring required.
## Troubleshooting Common VTX Control Issues
| Symptom | Likely Cause | Solution |
|———|————-|———-|
| “Device Not Ready” in OSD | Wrong UART or protocol | Verify UART TX pad and Peripheral setting |
| Wrong power levels showing | Incorrect VTX table | Load manufacturer-specific VTX table |
| OSD shows but can’t change | VTX not responding to SA/Tramp | Check wiring; try reflowing solder |
| VTX stuck at low power | Pit Mode enabled | Disable Pit Mode in VTX tab or via OSD |
| Settings reset after reboot | No low ESR capacitor | Add 35V 470uF capacitor to power pads |
## Recommended VTX
For reliable SmartAudio control with excellent output power and clean transmission, we recommend the **Rush Tank Ultimate Plus 800mW VTX** available at [uavmodel.com](https://uavmodel.com). It supports SmartAudio 2.1, features a robust MMCX connector, and delivers exceptionally clean signal across all power levels with an included VTX table for easy Betaflight setup.
## Watch: VTX Control Setup Walkthrough
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