2. Materials and Tools

Here are the essential parts you will need if you want to build a similar robot. These items are available either from Pololu or from most electronic component distributors.

• Pololu micro dual serial motor controller
• Pololu robot chassis plate
• Parts to build the robot chassis, which come with our chassis combination kits:
  • Tamiya twin-motor gearbox (Tamiya #70097)
  • Tamiya ball caster (Tamiya #70144)
  • Tamiya truck tires (Tamiya #70101)
• PIC16F627 or PIC16F628 microcontroller in a DIP (dual in-line package) from Microchip. The 16F62X microcontrollers are the only 18-pin PICs that have a built in UART (universal asynchronous receiver and transmitter), which makes transmitting data serially (to the motor controller) very simple. The code presented in this project should be portable to any other PIC with a hardware UART; with the other PICs, you would have to write your own serial routines (which isn’t that bad since you only need to transmit, and the motor controller should handle any baud rate you come up with).
• Clock source for the PIC. We used a 4 MHz ceramic resonator with built-in capacitors; any crystal, resonator, or oscillator in the 1-20 MHz range should be fine.
• 18-pin DIP socket for the PIC. You may also want a socket for your motor controller; a crude way of obtaining a 9-pin SIP (single in-line package) socket is to cut an 18-pin DIP socket in half.
• Two long-lever, snap-action switches for use as bumpers switches.
• 3.6 V, 650 mAh cordless telephone battery pack (or three AA size NiCd or NiMH batteries in a battery holder). Cordless phone batteries are available in many consmer electronics stores (e.g. Radio Shack, Best Buy) and discount stores (e.g. Wal-Mart) for around $10, making them a great power source for small robots.
• General-purpose prototyping PC board (or proto board) with space for two 18-pin DIP sockets, the ceramic resonator, and whatever other electronics you might want to fit. Such boards are available from most electronics component stores, including Radio Shack (e.g. part number 276-150A). To avoid soldering, this project could also be done using a small wireless breadboard, such as the one used in project 2.
• Hook-up wire and solder for making all of your connections.
• Double-sided foam tape provides a quick way of temporarily mounting items such as the battery pack. Alternatively, you could use standard mounting hardware or cable ties for fixing your components to the chassis.

You will probably also want to use the following:

• Pushbutton switch and 10k resistor for a reset circuit
• Two 0.1 uF capacitors to solder across the motor terminals
• Power switch

You will also need these basic tools:

• Soldering iron
• Diagonal cutters
• Wire strippers
• Scissors
• Phillips screwdriver (for building the gearbox and ball caster)
• Hot glue gun (optional)