Older blog entries for gear21 (starting at number 9)

My printed circuit boards should arrive from ExpressPCB today! My bot hasn't run since I ripped it all apart to redesign a few things, and this is one of the last "major" changes. It will eliminate a huge part of the "rat's nest", as well as make it more modular.


Also, while I was at W@lM@art yesterday, they had a cheap (<$12) "remote control" truck. It's controlled by 4 wires connected to a simple left-right & up-down mechanism (like a really cheap radio transmitter. I ripped it apart, and it looks like it will work great for experimenting with. The control is a very simple mechanical h-bridge, but I'm just going to drop it for one of the H-bridge chips (the motors are pretty small). If you're looking for a cheap base, this one should work for basic projects...

This weekend I also got the OOPic to talk to my Palm Pilot via Serial connection. Works great! I can send it commands through a palm pilot. But I haven't decided which one to use - a laptop PC, or a palm. Programming the laptop is a lot easier, but the palm is nice and small, with longer lasting batteries.... decisions, decisions. I will most likely prototype on the PC.

I also started a OOPic related website on Friday. It's at OOPHQ.com. (OOPic Headquarters). If you have OOPic content, feel free to send it to me ;)

Two events have happened recently for my bot...

First, I completely messed up my "connection board" for connecting my oopic to the rest of the bot (basically, where I convert from the 40pin IDC cable to a board, then go to the different sub-systems)... It's so messed up, I have to scrap it. BUT, I finally sat down and used the easy to understand printed circuit board software from ExpressPCB, and laid out a nice board without so many wires that I can mess up. I'm reviewing it tomorrow, and I'll send it in tomorrow afternoon. I'll let you know how it comes out.

I also finally soldered together the CompSys1.com rs232 kit and installed it... My bot was talking to my pc through the serial connection in less than 20 minutes. I think this will help a lot with debugging, now that my oopic2 programs are getting more complex.

A quick note on soldering... If at all possible, DON'T use a radio shack $9 iron. Get a nice one with a fine point. And use flux. I used a $9 iron for years... and if I had known a Weller was this much better I would have sprung for it a long time ago... it's worth every penny.

The pics are up! I put them on my site as pdc01- pdc07.jpg. In case you're wondering, the structure is a spare 3.5" aluminum drive holder from my PC case. (Lian Li rocks, btw).

Looking down on the connection strips, the left is for +12 (unregulated), the middle is +5 (regulated), and the right is ground.

Other than essentials, everything is still removed, as I revise my mounting plans.

Ahh.... finally...rewiring complete and tested. Took a bit longer when there was a bad switch in my circuit, but once that was replaced, the new power distribution center is working great. I took some pics, but haven't uploaded them yet.

Now that I have a new "Power Distribution Center", I've been completely re-wiring the external switches, sensors, and everything else... It still looks cleaner, but it's taking a while.

I started planning out the new "control panel" orientation, and I bought some clear laser printer stickers, so I can correctly label each of the switches, lights, and the LCD that just came in from AllElectronics.com.

Also received an RS232 module that will make connecting and disconnecting to a serial line much easier. I ordered it from CompSys1.com this weekend, and it arrived yesterday. Looks neat... now all I have to do is solder it together and try it out! :)

15 Apr 2002 (updated 15 Apr 2002 at 03:21 UTC) »

I spent a good part of the weekend ripping out all the power and ground connections and rebuilding and rewiring the entire system. (new pics coming soon)

There were a couple reasons for this... First, wires were starting to go everywhere (esp. with the connections from the switches), AND I needed to add another +5v source (just a 7805) since I didn't want to stress the OOPic now that it will connect to the IR ranger. It looks much cleaner now...

I also decided on a name for the bot! Akhenaten. (The 18th Dynasty Egyptian Pharoh).

10 Apr 2002 (updated 10 Apr 2002 at 05:21 UTC) »

After getting a few new bits and parts, I came up with a much more reliable bumper system... Instead of the overly-complicated spring/hinge mechanism, I converted it to a simple stip of aluminum bent at the ends and near the center. It's simple and works better! The pics of the bumper are on the bot's site at http://www.gear21.com/scook/bot/.

Some of you may have noticed that if it runs into something in the middle, it won't set off the left or right switch... but that's why I have the GP2D12 IR range module *GRIN*.

This week I soldered up the "secondary board" to my OOPic2 so I can attach the 40pin IDE connector to it without soldering my OOPic board. From the secondary board, I have 8 outputs (enable,fwd,rev, and PWM-speed for left and right) and 7 inputs (5 contact switches, 1 IR module, and 1 A2D for battery monitoring). BTW, solder flux RULES!

Since the switches are bolted to the outer shell of the bot, the connections are made to an IDC header, that I can connect the switches to. That way I can remove the shell without having permanent wires attached. Using the internal pullup resistors on the OOPIC is going to make the switch circuits really simple and clean.

I got a couple emails about the wheels and gear motors. I bought the motors from www.sciplus.com about 8 months ago. They were from one of the battery operated kiddy cars. The output shaft was unique in that it was 2.25" in diameter and was divided into 10 sections. I was originally going to just replace the shaft completly, but as luck would have it, by breaking off every other section, it fit exactly into my lawn mower wheels. (shell1.jpg shows the wheel). This was an astounding bit of luck that it matched size, radius, and depth! After that, I bought two more motors as spares!

2 Apr 2002 (updated 2 Apr 2002 at 22:26 UTC) »

Finally posted some pictures of my as yet un-named robot. There isn't an index yet, but they can be seen at: http://www.gear21.co m/scook/bot/

The skeleton is built from aluminum pieces scrounged from around work (which is why it is almost exactly the same size as a 12u rack-mount network switch :).

I used "off the shelf" DC motor controllers after many variations of H-Bridges I built just didn't have the flexibility I wanted... For the new controllers, I made a "universal interface" using cat5 ethernet cable and rj45 connectors, so I can swap out drive methods (from connected switches, remote control, to onboard microcontrollers).

Originally I was using a parallel port on a laptop to send signals to the motor controllers, but the laptop was just too big, so I got an OOPic a few weeks ago, and have started using it as the brains...

This week, I'm making an interface to the OOPic so I can connect 5 contact switches and 1 IR range module for external sensory duty...

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