PIDFlight Lap Timer - English version

Who never took part in the post-training discussions, deciding by eye or sound who was the fastest (or not) pilot of the track. To add a scientific touch to the method, the RaceTtracker (from TBS) and the lapRF (from Immersion RC) arrived on the market. The ambition was to bring a real timing system, exit then all the unneccessary chit chat between pilots. After testing the first one, I was really sceptic and disappointed with the range ! After doing all the modifications and even a factory return, I never gained the necessary Bluetooth range to use the device safely (understand more than a few meters).

A new system, with a quite innovative idea appeared recently : the PIDFlight Lap Timer.
The concept is simple : you have to buy an app that is available on the Play Store (4 eur / year) and the hardware can be purchased online or can be assembled ; in fact plans are available under open source license.

Details

On the paper, the PIDFlight Lap Timer has many common points with it’s concurrents :

  • Android application available in different languages
  • Bluetooth, WiFI and USB connectivity
  • More than one pilot timing with one device (however less accurate)
  • Position and lap time thru speech synthesis, all info on the smartphone screen

Hardware

I made the choice to build the device with the components that are listed on the PIDFlight website. You will need :

  • Arduino nano v3 : https://goo.gl/TMtTzV - The main component, he has all the intelligence needed for the hardware part. He watches the values of the video receiver, analyses them and then pushes them to the transmission module.
  • RX5808 : https://goo.gl/C1LFpg - It is « simply » a well known video receiver. This component will be able to detect the drone fly-by.
  • HC-06 : https://goo.gl/6yBkA7 - Bluetooth module for transmitting the informations to the smartphone.
  • DT-06 : https://goo.gl/P8exGt - WiFI module for transmitting the informations to the smartphone.

Nota : you only need one communication module : the HC-06 OR the DT-07. The following configuration elements are for the WiFI module.

All elements were placed on a breadboard for testing because I was initially very sceptic of the system performance. Note also that the free functions of the Android app will not only let you test your phone compatibility but will also provide a test harness for the hardware part. Test it before buy, I love that !

Let us now transfer the firmware on the arduino (download link). For doing this, the command line is the following (I’m using avrdude on Ubuntu Linux, more informations for Windows on the PIDFlight website) :
avrdude -U flash:w:pidflightlap_2.5.0_PDFL.hex:i -e -p atmega328p -b 57600 -c arduino -P /dev/ttyUSB0

With :

  • pidflightlap_2.5.0_PDFL.hex : firmware to be installed
  • /dev/ttyUSB0 : the target (for Linux, in our case USB0). For Windows it shoul be something like -P\.\COM4

Now power on the device by connecting the USB port on your PC so that we can finalise the configuration of the WiFI module. Connect to the WiFI module using the WiFI on your smartphone (the module initiatisation is quite long - 1 min - be patient), select the network that is named something like DOIT_xxxx.
In a browser type then the following address : 192.168.4.1. The info screen is immediately displayed (Image 1).

Some more configuration steps are needed :

  • AP (Access point) activation : Module menu, then WiFI configuration. Change the SSID value (WiFI network name that will be displayed - I typed the value « PIDFlight Timer ») and the password (required to have a working secure connection, but not necessary - I used « pidflight »).
  • TCP server port : Module menu then Networks. Change the port number (TCP Local Server Port) by replacing the 9000 value by 23 (Image 3).
  • Serial link for the connection with the Arduino : Module menu then Serial. Change the transmission speed (Baud Rate) from 9600 to 115200 bauds (Image 3).

After each step, do not forget to restart each time the module : More munu, then Restart.

The access point for the Android application is now ready for connection.

The Androit app

First of all you have to install the app via the Play Store. Before connecting, verify or change the settings :

  • Connection type : WiFI
  • IP Address : 192.168.4.1
  • Port : 23

Then, connect to the hardware using the button/icon located top right.

You now need to adjust the video frequency (it should be the same as the one used on your FPV gear) and the pilot name. Calibrate the whole system by placing it near the gate and power your drone at the opposite side. Click on Calibrate. Thats’s it ! The device is now ready !

Conclusion

The first tests on the range are more than positive and I’m really impressed ! Is it because the WiFI module ? Probably. I transferred all the components on a prototype PCB to ease transportation and on-field testings. I finally have now to test it over and over in real conditions.

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