Drum roll, please!
The Office Chairiot Mark II is now wirelessly controllable!
It's not the most attractive enclosure, but it was fast and easy to make and it serves the purpose for now. I'll design a proper one later. The "Paddy" Wagon attachment (see previous article) isn't controllable without a controlling device of some sort, so for now, this is it.
Wireless technology is Xbee (Zigbee). Since there are only two nodes in this Xbee network, I'm using them in "transparent" mode, so they act like an invisible 115,200 BAUD serial cable. These Xbees are S2 versions with extended range. Here's the antenna (you can see the Xbee board and adapter under the hot glue):
The Xbee boards have a little "Associated" LED to indicate that they're hooked up to their friends. I extended that out to the case of the remote because it's fun to watch it blink.
The joystick is nearly identical to the one on the crazy control panel, except this one is lower-profile and doesn't have the ball at the end.
The switches are the same brand and type as on the big control panel. I used them because I have a bag full of them. They're sturdy and clicky. I like 'em.
The inside of the repurposed gift tin (I think it had a wallet in it at one point) is a bit of a rat's nest, right now. When I have more time (after the next two events), I'll built a proper enclosure and PCB for inside.
I used a little black cardboard to keep things safely separated. Hot glue like usual to lock things in place. The joystick is at a 45º angle to make "mixing" the axes of the stick inputs for simpler differential steering, just like on the big control panel. Why waste CPU cycles mixing the input values when a twist of the stick does it for you?
All of the switches share a ground wire, except for the power switch, which is there to simply interrupt the power from the LiPo battery. Super quick and easy to get all this together and working. Love it when an on-the-fly engineering plan comes together so easily.
Like most of my projects, this one is controlled by a flavor of Arduino. In this case, it's the Arduino Pro, which is a no-frills board with holes for soldering to, no headers or anything. I like these for quick builds because I can program them using the Atmel AVR ISP Mk II programmer. I don't need the Arduino bootloader at all, which also means I don't have to have an on-board USB port when I don't need it. This Pro is running at 8 MHz and only 3.3V to match with the Xbee board.
Thanks to the SparkFun USB LiPoly Charger - Single Cell, it was VERY trivial to use a slim rechargeable battery inside the remote control.
The battery was saved from certain death when a friend offered a nearly new Mohpie Juicepack (battery pack phone case for iPhone) to me when he upgraded his phone. I already owned one myself, so I took out the battery and kept it for a future project. It's 2Ah, so should be plenty of juice for pushing the Office Chairiot base around. The other cool thing about that charger board is the LED to let you know when it's finished (red light turns off when completed), so I broke out that LED to the outside of the case, as well:
Overall, I'm very pleased with the outcome. Not thrilled about the box, but I needed a solution FAST. This is why I keep a box of mint tins, gift tins and other miscellaneous containers around. Temporary (or not) enclosures that stay out of landfills. Like I said above, I'll CAD up a cooler box later.