I wanted to build something quick and fun with my newfound PIC knowledge. I had been wanting to build my own version of Frits' Little 8 for a while, so I decided that now was the time. I was thinking that the two Solarbotics GM10 motors that had failed as drumsticks might work just fine as motors -- the gears tended to jam when the drumsticks hit stuff, but as motors they wouldn't be subjected to the same types of sharp, sudden stresses. So I went down to Home Depot and grabbed a handful of free paint mixing sticks, soldered up a quick circuit board to hold sockets for the PIC and the SN754410 motor driver, a 7805 voltage regulator, a set of pins for programming the PIC with ICSP, some female headers to mount the RF receiver, and a bunch of screw terminals to hook up all the peripherals.
I've already got some old Atari joysticks that I want to use to build a simple RF transmitter like Frits', but I haven't got serial reception working right on the PIC yet. I can transmit just fine, but when I try to receive, the incoming text is all garbled. So for now, Little PIC just runs around and bumps into stuff, as you can see in the video. And since the only switches I could find have much shorter metal blades than Frits', my robot can easily get stuck if he runs into a corner just right.
Eventually I want to glue on some extensions for the whiskers, and get the serial comms working so I can control the robot with the joystick. I figure he can run around at random until he receives some instructions from the wireless receiver, and then he'll just follow those and work as a remote controlled robot. If he goes 10 seconds or so without receiving any instructions, he gets bored and goes back to running around on his own.
Wow i think ill make one of those too! I dont have gm10 motors but i found tiny dc motos for 1$ each at a local store and i have some mouse wheels i can use as tires. i also got a ton of paint sticks.
The home made board you made is what i dont know how to make. would you mind posting a pic of just the board you made so i can try mimic it? also did you drill through the microswitches?
Sure, I’ve updated the post to include pics of the board. Good luck with that though Unlike my previous robots, with this one I didn’t take the time to carefully layout the circuit on paper before soldering it up, I just kind of played it by ear. So the result is a little messy, with several layers of wires running over each other. You’d probably do better to do what I did, and look at Frits’ Little 8, and base your circuit on that.
My switches already had holes, but they were just slightly too small for the 4-40 screws I use for everything, so I re-drilled them just a hair larger to let the screws fit through easily.
It wasn’t hard to make it, since I was lucky enough to find all the parts at local stores. Radio Shack carries the 5.1v zener diodes, but I had to go to my local non-chain store for the 8.2v zener. If I had had to mail-order any of the parts, I probably would have just paid the $10-15 for a pre-built one.
With that said, it is kind of frustrating that this JDM programmer depends on proper serial port voltages, and the only machine I have that provides the right serial output is my desktop machine, which is on the other side of the house from my electronics work table. I’ll probably be ordering some USB-capable programmer just so that I can work from my laptop out on the work table. In the meantime, though, this programmer works just fine, as long as I’m willing to walk back to the bedroom each time I want to update my program
Not sure if this’ll work since I haven’t used the chip myself yet, but maybe you could add a MAX232 transciever chip to get the programmer more robust regarding the serial port voltages. As far as I know it expects 5V as input and generates proper serial voltages. I’ve seen this in a lot of development boards for ARM uC’s that was programmed through the serial port (although that version was the 3.3V MAX3232 chip).
Hmm, if that worked I’d have expected to hear about a revised JDM programmer circuit utilizing it. But it’s worth a shot. I’ll order a few and play with them. Thanks for the tip.
Dan, been out of pocket or I would have chimed in earlier - this is a very cool bot. I thought of something when I read about the extended wiskers – instead of gluing them on, what about using a female spade type butt connector? I saw them at Walmart and thought about it. They have a large range of them in the car audio section and you can buy just a few.
One like the blue ones in this picture - the blade of the switch becomes the male spade.
That’s a great idea. I’ve already got a bunch of those on hand, never occurred to me to use one like that. Thanks, that will probably be a lot easier than trying to get hot glue to stick
