This page contains a list of commonly asked questions and the corresponding answers. Please use the Contact page if you have a question or issue that is not covered here.

Race Timer

Isn't this the same race timer as on website?

Yes, this is the same timer, resources and person behind race timer. I am moving all of the content to this website.

When testing the timer, the race finishes instantly with lane times around 0.1000 seconds.

The timer (Arduino) is 'seeing' a signal from the finish line detector (the phototransistor) that it is sensing dark (no light shining on it) which is processed as if a car is crossing the finish line.   This can be caused by a few different things:
1) The most common cause is incorrect polarity on the phototransistor - the emitter lead needs to be connected to ground. Please refer to Timer Construction page for more information.
2) Another cause can be that the light source (LED) is not aligned to the phototransistor or is too far away.
3) Another cause can be a bad connection on one of the phototransistor's leads to the rest of the circuit - check that each solder joint is good.

When compiling the sketch, I get multiple 'redefinition' errors.

This is usually caused by having multiple copies of the sketch in the same folder. For example, if you make a backup of the original before making changes. To solve this issue, move all extra copies of the sketch out of the folder.

Can the Adafruit 1.2" displays be used with the race timer?

Yes, with a little extra work they can be used.  Please refer to Timer Construction page for more information.

When compiling the sketch (after installing the Adafruit libraries) I get errors about an 'ArduinoRobot'.

This is an old issue from when the Adafruit libraries were installed manually.  Current versions of the Arduino IDE have a library manager to handle library installs and this should not be an issue.

This is caused by a conflict between different versions of the Adafruit libraries.  The simplest solution is to delete (or move) the Robot_Motor and Robot_Control directories out of the library's directory.

The PDT3 program (or one of the windows) is stuck minimized.  The lane place/time display is small and will not resize.

Hold the Ctrl key down while opening the main program (or the window).  This will force the program (window) to open normally, discarding the previous size and position.

What license is used for these resources?

All code (Arduino sketches), circuit schematics and construction plans are licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a copy of this license, visit or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA.

Last updated: 22 Nov 2019