Driving a robot - with a flick of the wrist

I got hold of a TI Evalbot Stellaris MCU development kit the other day together with the necessary firmware enabling it to be driven from TI's other geek-magnet, the MSP-430 based Chronos sports watch.

The robot is manufactured just like a plastic model aircraft construction kit. All the electronics is fully assembled: all you have to do is knock out the various parts from a pre-cut PCB and screw them together. The wheels are tricky, consisting of three PCB disks held together with self-tapping grub screws. A clamp or vice is useful here as you drive the screws through with the supplied Allen key. Once you have forced the wheels onto the axles, the rest is easy. Push the batteries in, press the ON button and the robot bursts into life moving about randomly, making precise turns when one or both of the front 'bumper' switches makes contact with an obstacle. It also emits entertaining noises every time it hits something. Movement is slow thanks to the lovely brass gearboxes on the tiny motors so although it could be used in a Micromouse maze - it won't break any speed records!

This is certainly no toy: it really is a 'proper' development kit bristling with communication and expansion sockets including a micro-SD slot. There is even quadrature encoded feedback from optical sensors on each side of the wheel disks.

Phase 2 now consisted of linking the Chronos watch to provide wireless remote control. A TI wireless kit (CC1101EMK868-915) was obtained and the 868MHz receiver plugged into the expansion sockets either side of the MCU chip.The rather tall antenna looks somewhat out of proportion, but you can allways stick a flag on the top!

The firmware on the Evalbot needs to be changed, for which the LM Flash Programmer Tool (ti.com/stellarisware) is needed together with Windows drivers (ti.com/lm_ftdi_driver). My PC refused to accept the latter, their being incompatible with the 64-bit OS. A switch to a 32-bit machine solved that one. The binary file for the program is lodged in the DesignSpark Knowledge base and TI should be making the source code available any time now.

The watch requires no re-programming, just a few button presses to turn on its wireless transmitter and away you go, twisting and turning your wrist to go forwards, backwards and steer, thanks to the built-in accelerometers. The robot even emits a warning horn noise when reversing....The speed in each direction is proportional to tilt: holding the watch level bringing the robot to a halt. Hours of fun to be had, but at some stage I guess I'll have to justify the purchase of these 'Development kits' to the boss!

P.S. If you can make it to the Embedded World 2011 Show at Nuremberg next week the Evalbot and Chronos watch will be on the RS stand for you to try your hand at driving. Two Evalbot kits will also be given away....