3pi Line follower


I have problem about my pololu 3pi robot. Can u helps me to solve this problem? I am new in this industry…I have problem about to make my robot moving with line follower code. Whats is the steps to make my robot moving?
What is the suitable software must i using? Whats is the Line follower code? How to compile and run the Line follower code using the software? How to upload the code into robot?

Can u help me? I really need your help…


You can find information and example code for your 3pi robot in the Pololu 3pi Robot User’s Guide.

For information on how to get started with software and programming your 3pi you can use our Pololu AVR Programming Quick Start Guide.

Other example projects and information can be found on the 3pi product page under the “Resources” tab.

I hope this helps you get off to a good start!


i want my pololu 3pi bot to follow a line that is 2.5 cm in width.
so how can i do it?
i thought that using the outermost two sensors and the middle one will do the job but i cannot come up with an code
so any kind hearted person out there who could write me up a code with the specifications above and also see the image
it has to stop also at the last point.
thnks in advance
hope u’ll rply at shitizgoel@yahoo.co.in


This sounds like homework or a competition. You probably won’t receive complete working code from anyone, but if you ask for help with a specific issue on code you’ve been developing, you’ll definitely receive some good guidance.

That said, it sounds like you’re new to line-following in general. I’d check out these links.

Line following, from the 3pi manual.

More line following from Tabletop Robotics.

Code is available from both locations.

Also, if you could share the code you’ve developed thus far, I’m sure someone (such as myself) would be happy to point you in the right direction if you’re having problems.


Thanx for adressing my question.
the thing i wanted to know is that what command should i put in the basic code (provided on this site) so that it stops at the last and doesnt stop when all 5 sensors wil be on black line during the loop that is given on top of the track ? :confused:

What you’ll need to do is keep track of the number of times you’ve encountered an all-black region of tape. Since you know the layout of the course, you can write code for the 3pi that will make it skip over the 1st and 2nd (i.e., the two points where the 3pi crosses the line, on the loop halfway through the course) black regions it encounters, by simply continuing to move forward.

Sir what is the code to include that counter function in the program?

While I’m afraid I don’t have time to provide and test code for you, I can certainly point you in the right direction.

What you’ll need to do is keep track of when all five of the 3pi’s QTR sensors return a value greater than some threshold; 1500 is a good start. Once they all read greater than 1500, wait until they don’t anymore. Once this happens, increment your counter once.

As long as your counter is less than 3 (assuming you place the 3pi after the starting circle, not on it), any all-black regions can be ignored, and the 3pi can simply continue forward. Otherwise when on all-black regions (i.e., and the counter is 3 or greater), use the PID line-following code as you normally would.