Hack a HEXBUG Spider for Serial Control with a TI Launchpad
The HEXBUG Spider from Innovation Firstis a fun toy robot you can buy from RadioShack or Target for less than $25.00. The Spider can move forward, backward, and turn left, and right.
The transmitter has its own microcontroller and power supply (two 1.5volt button cells). There are four buttons each connected to a pin on the microcontroller. When a button is pushed, the microcontroller pin is shorted to ground. There are no external pullups.
With this project the TI Launchpad is connected to the four button signals on the transmitter. The transmitters microcontroller generates the IR signal that actually controls the robot.
Six connections between Launchpad and transmitter (forw,back,left,right,bat+,gnd)
Opening the transmitter can be done using just a flat screwdriver. Simply pry the four plastic tabs (two on each side) using the flat screwdriver. The top of the transmitter comes right off.
The transmitter has convenient test pads at each signal making it easy to solder wires to.
You will also need to solder a wire to the ground pad in the upper left corner of the image above. I also soldered a wire to the bat+ pad for a future project. It is not needed for this project.
Connecting the TI Launchpad to the Transmitter
The Spider is controlled using a simple serial protocol. The first character received by the MSP430 after reset MUST be a ‘o’ at 2400baud (see this article for the reason why). After the ‘o’ is received, the MSP430 will return a ‘>’ at 2400baud. Sending a ‘f’ moves the robot forward, a ‘b’ moves the robot back, a ‘r’ turns right, and a ‘l’ turns left. Sending a ‘s’ stops the previous motion.