Overview of the expansion kit for 3pi mobile robot
The expansion kit for 3pi mobile robot is a printed circuit board allowing you to add very easily your own components to the 3pi mobile robot of Pololu. It has the exact same size as the robot and is mounted right above the wheels. The expansion kit is very easily removable.
The shape without cutouts of the expansion kit's PCB gives you lot of space for your own components but require that you remove the LCD screen from your Pololu 3pi mobile robot. If you prefer to keep the LCD screen, you can choose the expansion kit for 3pi mobile robot of Pololu with cutouts. Both models exist in red (with, without cutouts).
The expansion kit for 3pi mobile robot contains a printed circuit board with with holes spaced on a 0.100" grid, two extended 2×7 male headers, 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.
Personalize our mobile robot with the expansion kit for 3pi mobile robot
The expansion kit for 3pi mobile robot offers you a large free space for your componants. It has room for two 0.6" 40-pin DIP (dual in-line package) components, such as the ATmega32 or a lot of smaller DIP components. Prototyping space goes to the edge of the expansion kit's PCB, allowing you numerous interresting locations to mount all kind of sensors, from bumper switches to range-finders.
Once assembled, the expansion kit's PCB gives you access to the ATmega168’s free/jumpered pins, the LCD pins, as well as to the three on-board voltages: VBAT (battery voltage), VCC (regulated 5V), and VBST (regulated 9.25V that is supplied to the motors). It is also connected to the 3pi mobile robot's power button and battery charge port, allowing you to add your own power buttons and charge ports.
The silkscreen of the expansion kit's PCB allows you to see how the pads are connected the electrical connections are on the bottom side. You can cut the copper traces with a sharp knife if they interfer with your prototype.
The two unused I/O lines on the 3pi mobile robot’s microcontroller are its serial transmit and receive lines. This means that you can add a second microcontroller or microcontroller board, such as a Basic Stamp, or Arduino Nano, to the expansion kit's PCB. This second microcontroller would deal with all of the sensors and additional hardware you added on the expansion kit's PCB and control the base via serial commands. Pololu releasedserial slave program for the 3pi mobile robot that turns it into a serially controlled platform that waits for the orders of your microcontroller
Assembly of the expansion kit for 3pi mobile robot
The supplied header pins allow you to establish all of the necessary electrical connections between the expansion kit's PCB and the 3pi mobile robot. We recommend that you fully assemble the 3pi mobile robot and its expansion kit in the following order before you solder anything. This will ensure that once everything is soldered in, the expansion platform will align properly with the base.
- Place the 2×7 female header and one of the 2×1 female headers into the proper holes in the 3pi mobile robot as shown by the yellow rectangles.
- Insert the long ends of the 2×7 and one 2×1 extended male header into these female headers, and insert an extended 2×1 male header into the battery charge port. Remove the LCD and insert the remaining extended 2×7 male header into the LCD port. Place the expansion kit's PCB so the tops of these male headers seat in the proper places, as marked by the rectangles in the picture below. Note that the expansion kit's PCB mounts with the silkscreen facing up.
- Slip a nylon spacer between the base and the expansion kit's PCB so that it lines up with the mounting hole on the 3pi mobile robot. Insert a screw from the underside of the base up through the base’s mounting hole, the spacer, and the mounting hole on the expansion kit's board. Holding the head of the screw against the base, twist the nut onto the other side, but don’t tighten it all the way. Repeat this process for the three remaining screws, and then tighten them together so that the expansion kit's PCB is aligned well with the base.
- With the screws holding everything in place, you can now solder the female headers to the 3pi mobile robot and the male headers to the expansion kit's PCB. Once everything is soldered in, you can remove the screws and pull the expansion kit's PCB off of the base it should look like the one in the picture below.
After assembly you will have a single 2×1 female header left over. You can use this to create your own battery charge port on the expansion kit's PCB.