User Manual

libraries/m3pi]; many of the serial-slave commands are supported by the m3pi library. To use the library

in your mbed program, either base your program off of an existing m3pi program or click the “import

this library into a program” link on the m3pi library webpage.

If you are using the m3pi expansion kit to upgrade your 3pi robot to an mbed-controlled

m3pi robot, you should use your AVR programmer to load the serial slave program

[https://www.pololu.com/docs/0J21/10.a] onto the 3pi. The source code for the serial slave

program is included with the Pololu AVR library [https://www.pololu.com/docs/0J20], as is a

precompiled hex file.

Technical Details

To control the base, the mbed communicates serially with the 3pi’s serial slave program at 115,200

bps. If you ordered a fully-assembled m3pi robot, the included 3pi ships with a special demo program

that waits for five seconds on startup for a serial command. If the 3pi does not receive a serial

command during this initial five seconds, it goes into a demo mode that shows off the various features

of the 3pi. To avoid going into demo mode, the mbed should at least send one command within the

first 5 seconds of turning on (a good choice would be m3pi.cls(), which clears the LCD).

For more information on how the mbed connects to the 3pi base and other m3pi peripherals, see

Section 4. The m3pi mbed library makes it possible to use the m3pi robot without knowing exactly

which pins connect to which peripherals, but advanced users might find this information useful if they

are modifying the library or writing their own.

3.b. Wixel in Control

The m3pi robot has a socket for a Wixel module [https://www.pololu.com/product/1336]. The Wixel can be

used with its stock wireless serial app to easily add wireless functionality to your m3pi robot, or you

can take it a step further and program it to act as the main controller of your m3pi.

As long as the m3pi expansion board has shorting blocks on its three serial jumpers and the 3pi robot

base is running its stock serial slave program (or the most recent version of the 3pi demo program),

a socketed Wixel can control the 3pi base through a series of serial commands while simultaneously

performing high-level tasks like wireless communication, route planning, and sensor processing.

There is currently no Wixel library specifically for controlling the m3pi, so there is a bit more

programming involved in getting started with the Wixel than with the mbed. The serial commands for

controlling the 3pi base are documented in the section of the 3pi user’s guide on the serial slave

program [https://www.pololu.com/docs/0J21/10.a]. The 3pi robot included with the fully-assembled m3pi is

pre-programed with this serial slave program.

3. Using the m3pi Page 21 of 39