m3pi Prototyping Space

I recently upgraded my 3pi to a m3pi, and I also got a MaxSonar to go with it. I read about the prototyping space on the m3pi board, but I couldn’t find anything on where the ports are connected to the mbed, if at all. The sonar can send input in 3 ways, but the one I would like to use is the analog output. Could anybody help me get this to work?


Are you asking how the mbed is connected to the m3pi prototyping space? As it says in the m3pi User’s Guide, “The through-holes are connected in a breadboard-like pattern denoted on the top silkscreen by thick, white lines between holes. You can use this prototyping space to cleanly and easily add sensors or other custom circuits to your m3pi robot. The traces that connect the prototyping holes are all on the underside of the expansion PCB and can be selectively cut to modify the configuration of the prototyping space.”

The following picture shows the silkscreen:

Does that help?


Somewhat, but I need to know which areas on the prototyping space are connected to which pins on the mbed.

That should be clear from the picture. Maybe you can ask about a specific pin as an example?


Looking at the schematic of the expansion board, I can’t find any free pins, although I could be wrong. All I need is a free pin that I can read analog or digital with. I don’t have an xbee or Wixel connected, if that helps.

EDIT: It appears that P24 on the mbed is free. Where is it connected on the expansion board?

There are a lot of free mbed pins on the m3pi, and you can always cut traces to peripherals that you do not care about.

Anyway, here is the mbed pinout:

From the picture you should be able to see that pin p24 is the fourth pin from one corner of the mbed. Here is picture showing what it connects to - one pin where you plug it in, plus one other pin to allow you to access it. This particular pin is only accessible in one location, but most of the others are connected to a few other points in a column. Does that clear it up?


Yes. Thank you very much.

I have an m3pi, and it looks like there are few spare pins. I have a Sharp distance on pin 12, no problem. It’s set to be a DigitalIn, even it shows to be miso of SPI. There can be conflicts on some pins, however. That’s why we have to tinker and learn, and make fun.