CMS Lap Timer Pro

The Cantrell Motorsports Lap Timer Pro is the easiest to use GPS-based lap timer, data recorder, video recorder, and performance analysis app available for iOS and Android devices.

Main Features


Overview of Operation

Modes (screens) are selected using the Mode button in the lower left corner of the display.

The Recorder is used to record data & video. Recorded data is saved to Runs. Videos are saved in the Photos app.

Runs is used to organize data runs and to display summary information for each run.

Analysis is used to analyze & compare data in Runs. Analysis is also available as a Mac OS app.

Video is used to view recorded videos with data overlaid on the video. On iOS, Video is also used to export video with data overlays to the Photos app and YouTube (via the Photos app). Videos consume approximately 1GB of device storage per 12 minutes. Use the Recorder screen to check the available storage before starting a session; otherwise, video may not be recorded. Minimum recommended for a 20 minute session is 4GB.

Settings is used to enter information such as the driver name, car name, location name and to set various app preferences.

Locations is used to view lap times using the CMS Cloud Service.


External GPS Modules

Due to limitations of the phone's built-in GPS (Location Services), the data may suffer from inaccuracy. Use of the built-in GPS is intended for demonstration purposes only and will generally provide useful data only at relatively slower speeds.

For iPod Touch, iPad, and older devices that do not have built-in GPS, the use of an external GPS module is required.

An external GPS module is required for high speeds.

Recommended External GPS Modules

GPS Module Notes
Dual XGPS160 Bluetooth GPS

10Hz update rate

RaceLogic VBOX Sport Bluetooth GPS

10-20Hz update rate

Dual XGPS150A Bluetooth GPS

4Hz update rate

Requires this firmware update

Bad Elf GPS for Lightning Connector

10Hz update rate

Emprum UltiMate GPS

5Hz update rate

Requires this adaptor or this one with a cable extension on devices with a Lightening connector; iPhone 5+, iPad Air, iPod Touch Gen 5, etc.


Mounting the Device in the Vehicle

Mount the device securely.

The device or GPS module must be mounted with a clear view of the sky so that it can receive a strong GPS signal; somewhere on the dash or windshield are good positions.

The device may be positioned vertically or horizontally. It should be reasonably level horizontally and vertically, and face toward the back of the vehicle. If you do not need to see the screen, the device may also be mounted flat; screen facing up and top facing the front of the vehicle.

When using an external GPS module, it is possible to ignore the device's orientation; it can be kept in a pocket or glove box for example. In this case, use the automatically calculated GPS lateral and longitudinal G forces in Analysis.

The use of a power adaptor is highly recommend.

Recommended Mounts

RAM Mount Universal X-Grip Suction Cup Mount
RAM Mount Universal Rugged Adjustable Twist Lock Suction Cup
RAM MOUNT for iPod Touch

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