I hope this is a right topic.
I would like to practice the MCU programming. At first I would like just turn on one led. Is it possible with the pololu 3pi? Can I program it without the pololu 3pi library?
According to the schematic the pushbuttons are connected to the LCD. Is it right? How can I access them?
I am quite new in programming but I know the basics.
I have moved your post to its own thread. It sounds like you are looking to start learning the basics of programming. While you could certainly do that with a 3pi, there are only a few pins that are unused that you could use to experiment with and connect external components to. It does have a lot of built-in features, such as motors drivers, buttons, a buzzer, LCD screen, reflectance sensors for line following, a trimpot, and LEDs, and you do not have to use our 3pi library; however, if your goal is to learn and understand the hardware and connections along with the programming, you might consider something like an Arduino first. The SparkFun Starter Kit for Arduino-Compatible RedBoard comes with a lot of basic components to get you started, and the guide walks through several useful circuits to understand. The guide can be found in the “Resources” tab of the starter kit’s product page. Please note that this starter kit does not come with an Arduino, but it does come with an Arduino-compatible SparkFun RedBoard. If your ultimate goal is to control a robot, you might also consider the Zumo Robot for Arduino, which is an Arduino controllable tracked robot platform.
By the way, regarding your question about the 3pi pushbuttons and LCD, the pushbuttons and LCD on the 3pi are connected to some of the same IO pins (PB1, PB4, and PB5), but they can be controlled separately.
Thank you for your answer.
I checked the links that you sent to me. I am thinking about the Arduino Uno. It looks a universal controller with many example projects and tutorials. With the Zumo Robot I can have a similar robot to Pololu 3pi?
I found an interesting project with Xbee. If I want to use Xbee I need an Xbee Shield. Is that right? But I think I cannot use together the Zumo Robot, Arduino and Xbee.
The best if I send you a photo: cooking-hacks.com/wp/wp-content/ … C_0405.jpg
The Arduino board is upside down on the Zumo Robot and there is not enough space for the Xbee Shield. Have you got any idea how I can solve this problem?
To use an Xbee module with an Arduino, you would not need to use an Xbee shield, although it makes the connections easier. As long as you make the necessary connections, you can use the boards together. As far as using the Xbee module with a Zumo, you are right that there is not room for all of the boards together in the intended configurations. It is possible to use them together; although, it requires quite a bit of modification. You can see an example of a Zumo being used with an Xbee module in this YouTube video:
To answer your question about how the Zumo and 3pi compare to each other, both robots can be used to do tasks like maze solving and line following and both have different strengths and focuses. The 3pi has an LCD screen, built-in line sensors, and 3 user pushbuttons. The Zumo uses an Arduino, has an optional line sensor array, and a built-in accelerometer, gyro, and compass. Both robots have a few extra unused pins that can be used to add external sensors. I suggest reading the 3pi Robot and Zumo Robot product pages for more information.
By the way, since it sounds like you are interested in the Xbee module, you might also be interested in our m3pi Expansion Kit for the 3pi Robot, which offers a convenient way to connect additional devices (such as an mbed development board, Xbee, or Wixel) to a 3pi.