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Lap Timer for OpenTX v2.1.x

The goal is to have an advanced lap timer on your OpenTX compatible radio using as little controls as possible. It should be able to store race and lap data for analysis back at the computer.

See for a quick demo of the Lap Timer.

NOTE: OpenTX v2.1.x is required. Lap Timer does not work on OpenTX 2.0.x.


  1. Copy SCRIPTS/TELEMETRY/LAPTIMER.lua to your SD card's SCRIPTS/TELEMETRY folder. Create the folder if it does not exist.
  2. Copy the folder BMP/LAPTIME to your SD card's BMP folder. Create the folder if it does not exist. In the end you should have BMP/LAPTIME/S_SWHAND.bmp for example.
  3. Copy the folder SOUNDS/LAPTIME to your SD card's SOUNDS/<LANG> folder. <LANG> should be abbreviation of you configured language. For example, English is en thus the correct sounds directory would be SOUNDS/en. In the end you should have SOUNDS/en/LAPTIME/better.wav for example.
  4. For any model you wish to enable the lap timer on, from the Telemetry setup screen, add a new screen, choose Script as the Type, and LAPTIMER.lua for the script name.


When launching Lap Timer for the first time, you will be presented with a configuration screen. Here, you can change a few key settings:

  • Throttle Channel - Output channel for your throttle. This is used to detect when a race starts for the first time from the Timer page. The output channel is used instead of Thr stick values because the channel output may be overridden by Kill switches, for example. If the channel goes high, then your aircraft will take off.
  • Lap Switch - Switch you wish to use to indicate a lap was just completed. It is best to put this on a momentary 2 position switch. On the Taranis, SH is ideal.
  • Speak Better/Worse - If Yes, your radio will say "Better" if the lap you just completed is faster than your previous lap or "Worse" if slower. You can alter these sound files to your likings. They are located in the SOUNDS/LAPTIME directory and are named better.wav and worse.wav.
  • Speak Lap Number - If Yes, when a lap is completed, that number will be spoken.
  • Beep At Half Lap - If Yes, a long beep will occur when you reach the mid way point of the lap as defined by half of your last laps time. For example, say your last lap was 60 seconds exactly. At 30 seconds you will hear a long beep. If you are further than 1/2 way around the course, then you are doing better than you did last lap. If, however, you are not yet to the half way point, you are doing worse than you did last lap.


To access the lap timer program, press and hold your Page button. This will then display any Telemetry screens you have defined. If you have multiple screens, press the Page button until you are on the lap timer screen.

When first entering the Lap Timer screen, you will be presented with the Race Setup page. Here you set how many laps you wish to run. Press your Plus and Minus keys to adjust accordingly, then press Enter to accept the value and go to the Timing page.

The timer will automatically start when the throttle becomes active. To mark the completion of a lap, pull the SG momentary switch. Once you have completed all of the laps, the Post Race page will appear.

On the Post Race page you will see a summary of your race including lap times, average time, total time and the number of laps completed. You can then use the Plus and Minus keys to select Save or Discard. If you choose Save, your race and lap details are appended to a file on your SD card named laps.csv in the following format:

  1. Start Time (YYYY-MM-DD HH:MM:SS)
  2. Lap Number
  3. Lap Count (total laps for race)
  4. Time (in milliseconds, divide by 1,000 to get seconds)
  5. Average Throttle

NOTE: At this time, average throttle is not calculated but it is planned and added to the CSV export to allow for easy future addition.

Special Actions

From the Timer page you can press Exit to abort the race. For example, maybe you crashed on lap 2 of 5. This will take you to the Post Race page, where you will be able to save or discard the incomplete race.

From the Timer page you can press Menu to access the Race Setup page and change any parameters accordingly. NOTE: If you do this during a race, your race will be lost.

From the Race Setup page you can press Menu to access the Configuration page. There you can configure some basic Lap Timer settings that affect all races.

Release History

  • Version 1.0.0 - Jan 12, 2016: First public release, everything is new!


Lap Timer for OpenTX v2.1.x




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