This kit gives you everything you need to add a second level to your 3pi robot. The black printed circuit board matches the color of the 3pi and has cutouts that let you view the LCD below and make it easier to reach the power button, reset button, and programming header.
This kit includes a round printed circuit board (PCB) with holes spaced on a 0.100" grid, one extended 2×7 male header, two extended 1×2 male headers, one 2×7 female header, two 1×2 female headers, four 7/8" nylon spacers, four 1-1/4" screws, and four nuts.
The expansion PCB matches diameter of the 3pi chassis and mounts just above the tops of the wheels using the four included screws and spacers. Once assembled, the PCB has electrical connections to the base that allow you interface your own electronics with the 3pi robot, which is sold separately. These connections give you access to the ATmega168’s free/jumpered pins, as well as to the three on-board voltages: VBAT (battery voltage), VCC (regulated 5 V), and VBST (regulated 9.25 V that is supplied to the motors). Additionally, the expansion PCB connects to the base’s power button and battery charge port, allowing you to add your own power buttons and charge ports.
This expansion kit’s PCB has cutouts that allow you to view the LCD below and access the power button, reset button, and ISP programming header.
The expansion PCB is designed to provide plenty of prototyping space for your components. It has room for one 0.6" 40-pin DIP (dual in-line package) component, such as the ATmega32 in the picture below, or for numerous smaller DIP components. The prototyping space extends all the way to the edge of the PCB, allowing you convenient points to mount a variety of sensors such as bumper switches and range-finders. The silkscreen shows how the pads are connected; the electrical connections are on the bottom side. You can cut the copper traces on that bottom side (with a sharp knife or a small rotary tool cutoff wheel) if some of the pre-made connections interfere with your desired layout.
The two unused I/O lines on the 3pi’s microcontroller are its serial transmit and receive lines. This means that you can add a second microcontroller or microcontroller board, such as a Baby Orangutan, Basic Stamp, or Arduino Nano, to the expansion PCB. This second microcontroller would deal with all of the sensors and additional hardware on the expansion PCB and control the base via serial commands.