picAxe 18m2 Robots Look Out!

Bot builders look out!

Yes, it's controlled by simple BASIC programs, but holy moly! Someone took all the complaints I had about trying to use picAxes for anything but single solutions and "fixed" the picAxe 18m2 chip! I bought one from SparkFun for Five Bucks.

It goes beyond the otherwise fun 18x. It all started when I tried to get my little black box robot to do a little more than just run around avoiding objects. Yes, the bot is cool, and the 14m is a great little chip to run it around, but that's about it. I really wanted to be able to read the adc coming from the IR Distance measuring device, but about all I could do was make the bot run around and do some intelligent avoidance. I needed more program space!

So I decided to go back to the old 18x chip I had used in the original 1st robot, the dogBot. It had enough program space to have interesting behaviors, but had problems because the timers couldn't run at the same time. So drive the wheels with a pwm signal, but you'd have to turn off PWM, to get the servos to operate. It was cool, but even with the program space, I could only get bursty operation: See this video, you'll get the picture:



So the dog would pull itself forward, shut off the pwm, then pull forward again.

Originally, I was trying to run the thing off a 14m, but the issue was the timers, not the chip itself. Eventually, it could find the door and do simple things. But it wasn't the greatest.




Now I'm looking forward to using the 18m2 to make dogBot come back to life, though I may change it's form (like giving it two-wheel drive and steering?) It will do things different.

By experimenting with a small platform, I was able to run four programs at the same time. Now I don't have to jerk and hack the PWM and Servos, but can run all at once and give a smoother operation. Basically, I've told the platform to constantly read the distance from the object it is to avoid.

This is not much of a video, but it shows the platform slow down and stop, then back up and turn, then it just shuts off and waits till I press what used to be the reset switch and it starts out fast, slows when an object gets close and stops reverses and makes a siren sound. Once it backs out of the way of the object, it constantly beeps (showing me it is in slow down mode). Right now it can't just drive away, but it's only a test platform, not ready for prime-time.




But here's what happens so far... It's pretty nice, a lot better than run and look and run and look some more. I think the picAxe 16m2 is gonna make my life a lot more easy and things are gonna be more fun than work with the multi-processing in the m2 chip. I here it still has EEPROM bugs, but I haven't needed the extra program memory in any of my simple bots. Maybe I'll like the chip so much... Well, who knows?

Yet another Cheap Robot

Lately I've been reading about Arduino's controlling the ever faithful Rumble Bots. They don't fight any more, they just run around under autonomous control.

Bot Bodies - Rumble Bot

In the early days (last year?) I was playing around with wheels and gears and all sorts of things when I stumbled upon an old Rumble Bot. I had to look 'em up because they weren't selling new ones... They have a card reader built in and all kinds of things that would make them a fun Robot.

I was just concentrating on using the body for batteries motors and gears when I saw Deans article via Make magazine. Dean used Arduino, I had used picAxe. When I added up the costs, I discovered Deans Arduino powered unit cost more than mine, so I thought I'd dig out the old videos and put this thing up as a proper project. So here it is on the CwhatIcanDo website complete with videos and step by step overview so you can build one too...

Dean's arduino cost $30
His Ping unit costs $30

Doing the same thing but replacing even the Motherboard means:
08m (if you want to be fancy) $4
08 motor controller board $15
Sharp IR detector unit $15

You can use the upper part of the body like Dean. One cool thing, Dean put touch feelers in the arms of his last conversion, it's a great idea. Use the rear switch already mounted on most models for detecting objects when backing up too!

CwhatIcanDo Projects