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Obsolete Defines

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This page contains old user_defines.txt that have been removed or superseded by new defines.

New items should be added to the top of the list so the last entry here is the oldest. The order of each entry should be [code]definename[/code] followed by the original text of the documentation, ending with a separate paragraph "REMOVED [version] [replacement or reason for removal]".

Obsolete Defines

Enable antenna-switching diversity for RX that supports it. Safe to leave it on for hardware that doesn't have diversity except for DIY builds which did not populate the RF switch.

REMOVED 3.0. Diversity is now a receiver option, changed via Lua for devices that support it in hardware.

Change the RSSI thresholds used by the Dynamic Power algorithm. If the RSSI moving average is below DYNPOWER_THRESH_UP dBm from the sensitivity limit, the algorithm will increase the power output by one step. Similarly, if the RSSI is above DYNPOWER_THRESH_DN from the sensitivity limit, the power will be decreased by one step.

REMOVED 3.0. The dynamic power algorithm uses SNR which is defined per-rate so the thresholds are more complicated than 2 defines.

no sync on arm doesn't transmit sync packets while armed. This is useful for racing as there is less time & packets wasted 🗑️ on sending sync packets (one packet every 5 seconds if connected). HOWEVER if you are doing serious long range ⛰️, keep this disabled because, in the case of a sustained failsafe, the link can not be regained while armed.

AUX1 is the channel ExpressLRS uses to detect "ARMED", and this feature assumes that a low value of the arm switch is disarmed, and a high value is armed. OpenTX can invert your switch if you prefer it to be mechanically inverted. It is best not to enable no sync on the arm when you are first setting up ExpressLRS as it can be a source of confusion.

REMOVED 3.0. Replaced with "Race" telemetry mode, which also disables sending SYNC on arm.


These features enable lower latency 🏃‍♂️ and offset from the OpenTX radio to the TX. The first is lower latency which should be kept enabled. The second is more experimental and can lower the offset from the radio by tuning it as close as possible to 0, but is experimental (even in 1.0) and is best left disabled.

Both require OpenTX 2.3.12 or above. To install it, you will have to use OpenTX companion application.

Deviation radio users such as those with the T8SG v2/v3 should disable this feature.

You can also use EdgeTX.

REMOVED After 2.2.0. Sync packets were always sent regardless of if this was enabled, but the sync offset would just be wrong if it wasn't defined.

This enables communication with the ESP Backpack for over-the-air updates (env:FrSky_TX_R9M_via_WiFi) 🖥️ and debugging via WebSocket 🔍. Uncommented by default, does not need to be changed.

REMOVED 2.0 development. Replaced with USE_TX_BACKPACK.

Changes how the AUX channels are sent over the air. The default option is Normal Mode with 8x 2-position low-latency switches. Enabling HYBRID_SWITCHES_8 changes this to 1x 2-pos + 6x 7-pos + 1x 16-pos, with only the 2-position being low-latency. In Normal Mode, all switches are sent with every packet, in Hybrid Mode, only AUX1 is sent with every packet and the rest are rotated through. Note: The switch mode MUST match between the RX and TX. A detailed explanation of the differences between the two options can be found in Switch Modes, but 1. If only two position switches are needed, and they must be updated as fast as possible: Normal Mode 2. Almost everyone: Hybrid Mode (Put ARM on AUX1)

REMOVED 2.0 development, all switch modes are available via Lua configuration. HYBRID_SWITCHES_8 is always enabled / available.

Enable advanced telemetry support. This option must be enabled on both TX and RX. The following telemetry messages are supported:

  • GPS


Increase the telemetry rate with the ExpressLRS Lua script. Increase the rate until the sensor lost warnings go away. It is normal to set it up to 1:16 with 200 Hz refresh rate.


It must be enabled together with HYBRID_SWITCHES_8.

REMOVED 2.0 development, ENABLE_TELEMETRY is always enabled. Advanced Telemetry will only be sent if telemetry messages are received from the FC.

This enables 500Hz mode for 2.4 GHz RXes and TXes. The drawback is that you have to give up 25Hz mode to add 500Hz mode. It requires OpenTX 2.3.12 or Newer, EdgeTX or a Radio firmware that has CRSFShot or Mixer Sync.

REMOVED 1.0.0-RC9, this option is now always enabled and in turn, 25Hz has been dropped/removed.

This enables integration with Jye's FENIX rx5805 pro-diversity module

REMOVED Somewhere in the 1.0.0-RC cycle. Feature removed.

An option that adds faster initial syncing, by changing how long the receiver waits for a connection in each mode while not connected. This option is now the default, but disabling it can help to sync at lower packet rates (50Hz and below).

REMOVED 1.0.0-RC2 initial sync replaced with a full FHSS period wait

REMOVED 1.0.0-RC1 replaced with generic -DUNLOCK_HIGHER_POWER

If you are using a different channel than the default you need to edit 🔥 (or you may not be able to gain sync safely - the default is listed in #DARM_CHANNEL as AUX1 which is Channel 5).

NB This feature assumes that a low value of the arm switch is disarmed, and a high value is armed. If you have the arm switch reversed it will not work correctly and the link won't be established. For this reason, it may be best not to enable no sync on the arm when you are first setting up ExpressLRS as it can be a source of confusion.

REMOVED 1.0.0-RC1 AUX1 is always the arm switch now, no longer configurable

LOCK_ON_50HZ locks the RX at 50Hz mode from the power-up. (Only recommended for long range, and partly redundant with the previous feature.) Merged in Pull 143

REMOVED 1.0.0-RC1 not sure why this was removed