Step 3: Construction
The tube is screwed on to the base with just two screws in the side which go in to some slots on the brackets mounted on the Create with parts from my VEX Robotics kit. The back of the tube has an extra lip on it that dips in to the back end of the cargo bay, which helps prevent front-to-back rocking motions. The two screws are simple yet strong enough to be able to pickup the bot by the tube and place it wherever you want.
Physical connections from the Propeller to the Create itself consist of the Serial TX and RX pins, the 5v Regulated pin on the Create is connected to detect when the Create is powered ON, the Power Toggle pin is also connected. Also the Dock detect pin is connected so we know when we are Docked.
Holes for the Sonar were drilled and rubber grommets were inserted to hold the sonars. Five additional holes were drilled on the back for the buttons and an LED.
A board was added to hold the i2c bus and the Compass module. The Sonars and Text-to-Speech module are connected to the i2c bus. The Compass module is connectected to the Propeller via a jumper wire.
A Variable Voltage Regulator was used to drop the Creates VPwr voltage down to 9v before feeding the Propeller ProtoBoard, which has a 5.0v and 3.3v regulator. A fixed 9 Volt regulator would be fine as well, I just couldn't find one at the time. You must drop the 18v from the Create Vpwr down to 9 Volts before going to the Proto Board because the 3.3v and 5v regulators can't handle 18v input directly. Plus, the Proto Board doesn't have room for Heat Sinks so you want to drop the voltage as much as possible before getting to them.
Another board was added for the XBee Radio interface. The XBee has 2mm pin spacing so it doesn't fit on standard .001" breadboards without making a custom board.
The 9v regulator, XBee Interface, and maybe the HM55B Compass will all be mounted directly on the ProtoBoard on the next build.